the teaching outline of histology and embryology for...
TRANSCRIPT
Department of Histology and Embryology ,
Henan institute of traditional Chinese medicine
December 26, 2004
Prelector,Wanggen Liu
PrefaceHistology is a science which study the microstructure under the light
microscope(L. M)and the ultra-structure under the electron microscope of the human
body, and relationship between the microstructure and function. Embryology is a
science which study the development of the human body. The teaching purposes of
these subjects are to induce the students who acquire the basic theories and
knowledge of these two courses and gain relative basic skill training. By studying, the
students should achieve such level: to distinguish the L. M structure of varieties of
cells, tissues and main organs, to distinguish the ultra-structure of the main cells and
tissues of the body, to know the relationship between the structure and function , to
gain a systemic knowledge about the early development of the human embryo and the
development of the main organs, to establish a good basis for learning other basic and
clinical medical courses.
The basic teaching requirements of Histology and Embryology for medical
department of five- year system of traditional Chinese medical college have been given
in this outline . The contents in this out-line will be taught by lecture , practice,
individual study and so on.
According to the teaching plan of five-year system of traditional Chinese
medical college, the total teaching hour is 54. The proportion of lectures to
experiments of Histology is 2. 6:1.
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The distribution of teaching hours
Chapter Content Lecture practice
Chapter 1 Introduction 1 1. 5
Chapter 2 Epithelial Tissue 2 1. 5
Chapter 3 Connective tissue proper 2 1
Cartilage and bone 2 1
Blood 2 1
Chapter 4 Muscle Tissue 2 1. 5
Chapter 5 Nerve Tissue 3 1. 5
Chapter 6Nerve System(individual study) 0 0
Chapter 7 Circulatory System 2 1. 5
Chapter 8 Immune System 3 0
Chapter 9 Digestive System 5 1. 5
Chapter 10 Respiratory System 2 1. 5
Chapter 11 Urinary System 2 1. 5
Chapter 12 Skin(individual study) 0 0
Chapter 13 Sense Organs (individual study) 0 0
Chapter 14 Endocrine System 3 0
Chapter 15The Male Reproductive System 1 0
Chapter 16 The Female Reproductive System 2 0
Chapter 17 General Embryology (early development) 5 0
Total 39 15
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Chapter 1 Introduction
Congratulate all examine smoothly into Henan institute of traditional Chinese medicine.
Welcome all to go to my class to learn Histology and Embryology!
Learning objectives1. Know the research object and purpose of histology and embryology.
2. Know the common research technics of histology and embryology.
3. Know the relationship between the cubic morphology with varieties of
sections.
Teaching contents1. The research contents and the situation in medicine of Histology and
Embryology .
(1)Definition : Histology is a science which study the microstructure of normal human
body and the relationship between the structure and function.
(2)Study contents : As you know,our body is composed of a lot of cells,tissues and
organs.
Cell:you will learn the structure of cell in biology very detailed.
Tissue: composed of cell group :
Cell: is the structural and functional unit of the body. it is composed of cell
membrane 、cytoplasm and nucleus
Extracellular matrix (ECM) : is produced by cells
There are four basic tissue : Epithelial tissue,Connective tissue,Muscle
tissue and Nervous tissue.
Organs : We will learn the structure of all organs in each system. Each organ consists
of several different kinds of tissue.
Histology is a basic and important subject for medical college student. It is also
foundamental for further study other subject,such as
Pathology 、physiology、biochemistry and so on.
2. The common research technics of Histology and Embryology.
There are many methods and techniques used in studing Histology and
Embryology. Here,only introduce some basic methods and techniques.
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(1). Light microscopy:means to use the L. M to observe the preparations. The most
common technique is paraffin sectioning. All the processes will be learn in
practical class. The section is usually about 5-10μm. In order to see the structure
very clearly,the sections must be stained. The routine staining methods is H. E
staining methods. We use two dyes in this method.
Hematoxylin:It is basic dye. It can stain some components in blue. such as nuclear
chromatin and ribosome in cytoplasm. Such components are said to be
basophilia.
Eosin: It is acid dye. It can stain the protein in red. such as the protein in
cytoplasm and extracellular matrix. Such components are said to be acidophilia.
If the components are not easily stained by Hematoxylin and Eosin,such
components are said to be neutrophilia.
(2). Electron microscopy:There are two kinds of E. M:Transmission electron
microscope(T. E. M) and scanning elctron microscope (S. E. M).
1). Transmission electron microscope: mainly used to study the internal structure
of cells and tissues. The working principle in T. E. M is the same as that in L. M.
The difference is the section is ultra-thin section,usually it is about 50-80nm. The
E. M used a beam of electron in place of visible light that used in L. M. The beam
passes through the ultre-thin section ,then is focused on to a fluorescent screen
or photographic film by a series electronmagnetic lenses. Using the E. M we can
observe the extremely small structure within cells or in extracellular matrix. The
resolution of the T. E. M is about 0. 2nm. The ultra-thin section are stained with
heavy metal salts,such as lead citrate,in order to in crease structural contrast. The
flow of electron can be impeded by those stained tissue. Consequently,if very few
electron can penetrate these area to screen. Such area appear dark and are termed
electron dense. By contrast,are termed electron lucent.
2). Scanning electrn microscope:This method mainly used to study the surface
structure of the cells or tissues. The specimen for examination under the scanning
electron microscope is coated evenly with a layer of gold. A finely-focused beam
of electrons scans the surface of the specimen. The secondary electrons are
emitted from the surface and then collected by a detector. All the signals from
many points create an image on a cathode tube,showing the three-dimensional
surface structure on screen. The image also can be recorded on photographic
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film. It has very good depth of focus.
(3). Histochemistry
This method mainly used to study the properties,localizations,quantities of some
substance in the cell using histological method and
chemical,physical,biochemical,immunological,molecular biological method
together.
1). General histochemistry:There are many methods used for detecting different
kinds of substances. Here,introduce a method for detecting the polysaccharides.
That is Periodic Acid-Schiff(PAS) reaction. In this reaction,periodic
acid(HIO4)oxidizes certain hydroxyl groups of the glucose in glycogen to
aldehydes ,then,the free aldehydes react with Schiff’s reagent,a colourless basic
fuchsin,to produe an insoluble violet-red complex. The positive position(violet-red
position)of PAS reaction represent that polysaccharides exist there.
Chemical equation:
Periodic acid(oxidize) Schiff reagent
Polysaccharides(hydroxyl)-------↓-------aldehyde------↓-----violet-red complex
2). Immunohistochemistry
3)In situ hybridization
3. The relationship between cubic morphology and varieties of sections.
4. The common length unit of microscope , use the international unit system
correctly.
Practice contentsSpecimen of L. M: H. E stain, AgNo3 strain, histochemistry, PAS reaction,
alkaline phosphatase and so on. .
Electron micrograph: The structural pictures of the cell under the transmission
electron microscope. The structural pictures under the scanning electron
microscope. Freeze fracture, freeze etching pictures.
Demonstration: the manufactory processes of histological sections.
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Chapter 2 Epithelial Tissue
Learning objectives
Understand the general features and classification of epithelial tissue.
Understand the structured features and functions of varieties of covering epithelium.
Understand the L. M structure, E. M structured features and functions of microvilli and
cilia.
Understand the ultra-structure features and functions of varieties of intercellular
conjunctions.
Understand the position, L. M structure, ultra-structure and function of basement
membrane.
Know the conception of glandular cells, glandular epithelium and glands, and the
morphological classification of exocrine glands.
Teaching contents
1. Outline of epithelial tissue:
1. 1 General structural features:
(1)Epithelial tissue is formed by a large number of regularly and closely arranged
epithelial cells.
(2)Polarity:It has a apical free surface,which faces the body or the lumen of an organ
and gland,and a basal surface,which faces the underlying connective tissue. There
is a basement membrane between the epithelial tissue and the connective tissue.
(3)Avascularity:Most of the epithelial tissue have no blood vessel. The blood vesssels
in the connective tissue can provide the nutrition to epithelium by means of
diffusion through the basement membrane. There are a lot of small branches of
nerve fibers in the epithelium.
(4)The epithelial tissue have many functions:
such as protection,absorption,secretion and excretion.
1. 2 The classification and general functions of epithelium.
According to the function and structure,epithelial tissue can be classified as:
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Covering epithelium: protect
Glandular epithelium: secretion
Special epithelium
2. Covering epithelium: Cover the surface or line the cavity of the body. Epithelial
cells are arranged in one or more than one layers. According to the number of
layers the and shape covering epithelium can be divided into two kinds:
(1)Simple epithelium:
Simple squamous epithelium : endothelium and mesothelium
Simple cuboidal epithelium
Simple columnar epithelium: Goblet cell------mucinogen granule
Pseudostratified ciliated columnar epithelium
(2)Stratified epithelium:
Stratified squamous epithelium:keratinized and non-keratinized
Transitional epithelium
The structure of each kind of epithelium will be learn by yourself after class.
3. The special structures of epithelial cell : In order to adapt their function,The
epithelial cells differentiate some special structure on their free surface,lateral
surface and basal surface.
(1). Free surface: There are two special structure on the free surface.
1). Microvillus: It is small,slender,finger-like projection of apical cell surface
consisting of cell membrane and cytoplasm. It is about 0. 2μm in diameter. They are
too small to be seen clearly under light microscope. They only can be seen clearly
under E. M. But in some epithelium,they are numerous and form a visible striated
border which can be seen under L. M. Such as in the absorptive cell of the
epithelium in small intestine.
Structure:Under E. M,there are many longitudinal microfilament in the microvillus. The
basal portion of the microfilament are embedded in and interconnected with
terminal web,which lies in the apical cytoplasm just beneath the cell
surface.
Function:They can increase the aborptive surface.
2). Cilium: They are also the projections of cell surface. it is about 5-10μm long and 0.
2μm in diameter. They are much thicker and longer than microvillus. They are
visible under L. M.
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Structure:They also consist of cell membrane and cytoplasm. There are a pair of
microtubule in the center of cilium and nine doublet microtubules around
the central microtubules. At the base of each cilium,there is a basal body
located in the apical cytoplasm just below the cell membrane.
Function:They can remove some small particles from the cell surface. It mainly
distribute on the epithelium lining the respiratory tract,such as trachea and
bronchus.
(2). Lateral surface:In the lateral surface,There are cell-to-cell adhesions. we call them
cell junctions. Those structure only can be seen un der E. M.
1). tight junction:It also be called zonule occludens. They are belt-shaped
encircling the apex of the cell. Under the E. M,the tight junction show the fusion
of the outer layer in the two plasma membranes . There is no intercellular gap in
the fusion portion.
Function:The tight junction can prevent the substance pass through the intercellular
space.
2). Intermediate junction:It is also called zonule adherens. It also encircle the cell
just beneath the tight junction. There is a intercellular gap of 15-20 nm
containing some filamentous material. The cytoplasmic surfaces of inner layers
of two cell membranes show a thin layer electron –dense materialassociated
with terminal web.
3). Desmosome:It is also called macula adherens. They are small Plate-shaped
structure. There is an intercellular space of 20-30 nm be tween twocell
membrane. The space is filled with filamentous material. In the center ,there is a
dense line termed intermediate line. On the cytoplasmic surface of inner layers
of two cell membrane there are dense attachment plaques. 10 nm tonofilaments
pass into the attachment plaques and then loop back into the cytoplasm.
Desmosome is the firmest junction.
4). Gap junction:It is also called communication junction. There is an intercellular
space of only 3 nm. There are many connections between the two cell
membranes. Each connection is about 7-9 nm in diameter and is formed by six
subunit called connexins arranged around a central channel. The channel is
about 2 nm in diameter. The connections in opposing cell membranes are
connected to each other. The structure permit directly cell-to-cell interchange.
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If there are two or more than two cell junctions,these are called junctional
complex.
(3). Basal surface
1). Basement membrane:Basement membrane is a thin membrane between the
epithelium and connective tissue.
Structure:Under the E. M,the basement membrane is composed of basal lamina and
reticular lamina.
Basal lamina: produced by epithelial cells and about 50-100 nm in thickness.
Reticular lamina: produced by fibrocytes and composed of reticular fiber and
ground substance,
2). plasma membrane infolding:They are formed by infolding of basal membrane.
There are many mitochondria in cytoplasm around the infoldings. The infoldings
increase the basal surface.
3). Hemidesmosome:It is a half of each desmosome in structure occurred on the basal
surface. They have the function to fix the epithelial cell onto the basement
menbrane.
4. Glandular epithelium: Glandular epithelium and gland
(1). Concept:
Glandular epithelium:It is composed of cells which have the function of
secretion and synthesis.
Gland:Gland is an organ which is mainly composed of glandular epithelium.
(2). Classification of gland:According to having duct or not,Gland can be divided
into:exocrine gland and endocrine gland.
(3). Exocrine gland :It is composed of secretory portion and duct.
Duct:composed of simple or stratified epithelium. Duct can discharge gland secretion
to body surface.
Secretory portion:It is also called acinus. At the end of duct,composed of a layer of
glandular cells and a cavity in the center.
According to the nature of secretions,The glandular cells can be divided into:
Serous cell:It is also called protein-secreting cell. It is pyramidal in shape. The
nucleus is rounded and locates near the basal portion. There are a lot of
acidophilic granules in the apical cytoplasm(zymogen granule). They are
red in the H. E section. The cytoplasm is strong basophilic in the basal
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portion. there are a lot of closely arranged R. E. R. The Golgi complx
locates in the cytoplasm just above the nucleus under E. M. The serous
acinus is composed of serous cells .
Mucous cells :The nucleus is flat located in the basal portion. There are a lot of
mucous granules in the apical cytoplasm. The cytoplasm is stained lightly.
There are some R. E. R in the basal portion and Golgi complex above the
nucleus. The mucous acinus is composed of mucous cells.
Mixed acinus:is composed of the two kinds of glandular cells.
5. The physiologic renew of the epithelium, and the regeneration of the epithilium
after destruction. The types of glandular cell: protein secretary cell,
glycoprotein secretary cell, steroid secretary cell.
Practice ContentsL. M. Specimen: simple squamous epithelium, simple cuboid epithelium,
simple columnar epithelium, pseudostratified ciliated columner epithelium,
stratified squamous epithelium, transitional epithelium.
Electron micrograph: tight junction, gap junction, intermediate junction,
desmosome, cilia, microvilli, hemidesmosome, basement membrane.
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Chapter 3 Connective Tissue
Part I Connective tissue proper
Learning objectives
1. Understand the feature and classification of the connective tissue.
2. Understand the structure and function of varied composition of the loose
connective tissue. Know the features of fibers and composition of the matrix.
3. Know the basic structure and function of the dense connective tissue, adipose
tissue and reticular tissue.
Teaching Contents
1. General characteristic:
(1)Connective tissue is also formed by cells and extracellular matrix. It differ from the
epithelium. It has a small number of cells and a large amount of extracellular matrix.
(2)The cells in C. T have no polarity. That means they haveno the free surface and the
basal surface. They are scattered throughout.
(3)The extracellular matrix is composed of fibers,an amorphous ground substance and
tissue fluid.
(4)Connective tissue originate from the mesenchyme,which is embryonal C. T.
Mesenchyme is composed of star-shape mesenchymal cells and ground substance.
The cellshave multiple developmental potentialities. They have the bility to differentiate
different kinds of C. T cells,endothelial cells and smooth muscle cells.
(5)C. T has many function,such as support,connection,nutrition,protection and
transport.
2. Classification of C. T
(1)Connective tissue proper,include:
Loose C. T, Dense C. T, Adipose tissue and Reticular tissue. L. C. T is the most
common type of C. T
(2)Cartilage and bone
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(3)blood
3. Loose connective tissue: is the most common type of C. T and the most widely
distributed in the body. There are three elements in loose C. T: cells,fibers and ground
substance.
(1)Ground substance :
Ground substance is amorphous,homogeneous,jelly-like substance,in which the
cells and fibers are embeded. They are composed of proteoglycan and fibronectin. The
proteoglycan is composed of protein and glycosaminoglycan which
includes:hyaluronic acid ,chondroitin sulfate ,keratin sulfate ,heparin sulfate. They
form a large molecule compoud—the molecular sieve. It serve as a barrier to provent
the spread of bacteria and other microorganisms.
The fibronectin is the media to connect the cells ,collagen and proteoglycan.
(2)Fibers:There are three kinds of fibers in C. T
1). Collagenous fiber :It is the main fiber element in loose C. T. They are also the
most numerous. it occurs singly or may be collected in bundle . The bundle is white in
fresh state,hence it is sometimes termed white fiber,Each fiber is about 1-20 μm in
diameter.
consists of protein collagen Ⅰand Ⅲ which is secreted by fibroblasts. Under the
E. M a fiber is composed of fibrils. The fibril is about 20-200 nm in diameter . The fibrils
have cross-bandings at a periodicity of 64 nm. Collagenous fibers are extremely
tough. In sections,they are acidophilic and stained red by eosin.
2). Elastic fibers :
Fresh elastic fibers are yellow,hence termed “yellow fiber”. They are thinner
than Collagenous fibers. They are 0. 2-1. 0 μm in diameter. In spreaded
preparation,they are bright,weak pink,fine threads. They branch to form an irregular
network. They are purple when stained by Ocien. Elastic fibers are composed of elastin
and microfibrils. So they have the elasticity.
3). Reticular fibers : Reticular fibers are very thin about 0. 2-1. 0μm in diameter.
The fiber branch to form a delicate network. The chemical composition is mainly
protein collagen Ⅲ. They are not visible in routine H-E sections. Using silver
methods,the fibers appear as thin dark lines. For that reason,this fiber are also termed
argyrophilic fibers . There are less in loose C. T. They are mainly in the reticular
tissue,lymph organ,basement membrane and surrounding blood vessels.
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(3)Cells
1). Fibroblast:It is the most common cell in loose C. T. They are also the most
munerous and usually found in close to collagenous fibers. They are large ,flat
branchingcells. They are star or spindle shaped. The nucleus is oval with one or two
distinct nucleoli. Cytoplasm is weakly basophilic. Under the E. M,there are a lot of R.
E. R and ribosomes,well developed Golgi complex.
Function:The fibroblasts can form the fibers and matrix. They play an
importantrole in healing wound.
Fibrocyte:When the fibroblast become older or inactive they become smaller . The
cytoplasm is acidophilic because there are less R. E. R. They are termed
fibrocyte.
2). Macrophage:They are also termed histocyte. They are irregular in shape with some
short blunt processes. The nucleus is smaller oval or kidney in shape and
stained dark. The cytoplasm is acidophilic. Under E. M There are a lot of
fold ,microvilli on the cellsurface. the cytoplasm contain the primary
lysosome and secondary lysosome,. phagosome,pinocytotic vesicles,
microtubules and microfilaments.
Macrophage derived from monocytes of blood.
Function:(1)Phagocytosis:bacteria,virus,and foreign cells.
:(2)Antigen presenting role
:(3)Secrete:many bioactive product:lysozyme,interleukinⅠ,complement
3). Plasma cell:They are rounded or oval in shape. a nucleus is eccentric. Chromtin is
arranged radially like a wheel in the nucleus. The cytoplasm is basophilic and
contain aclear area near nucleus where is the site of Golgi complex and
centrioles. Under E. M:there are a large amount of R. E. R and ribosome. Plasma
cells are formed from B-lymphocytes.
Functions:synthesize and produce antibody(immunoglobulin).
4). Mast cell:Mast cells often located in group near the small blood vessels. The cells
are oval in shape. The nucleus is rounded ,small land stained dark. The
cytoplasm contain many crowded basophilic granules. They are water soluble
granules. The granule is enveloped by a membrane. The granules contain
heprin,histamine,eosinophil chemotactic factor(ECF)It can synthesize the
leukotriene in cytoplasm.
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Function:Participate immune reaction.
5). Fat cell:Fat cell are large,rounded cells. Fat cells contain a large droplet of lipid in
the cytoplasm. There is a thin rim(layer) of cytoplasm around the droplet lipid
and aflattened nucleus in the thin cytoplasm. In H-E section ,the lipid has been
extracted,left only a thin layer of cytoplasm and flattened nucleus.
Function:Synthesize and store the lipid.
6). Undifferentiated mesenchymal cells:They still have the developmental potentiality.
In response to certain stimili,the undifferentiated cell can differentiated into
fibroblasts,fat cells and smooth muscle cells. In structure,those cells are very
similar to fibrocytes,They are smaller than fibroblasts.
7). Blood leukocytes:In normal condition,there are some blood leukocytes in C. T.
These may include:neutrophils,acidophils,lymphocytes and monocytes.
Practice Contents
L. M. specimen: the spreading slide and section slide of loose connective tissue,
the section slide of dense connective tissue, adipose tissue and reticular tissue.
Electron micrograph: fibroblast, macrophage, plasma cell, mast cell, collagenous
fiber, elastic fiber.
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Part II Cartilage and Bone
Learning objectives
1. understand the structure and function of hyaline cartilage, know the features of
elastic cartilage and fibro-cartilage.
2. understand the structure of osseous tissue and diaphysis of long bone.
3. know the processes of formation of bone and its remodeling .
4. Know the structure and role of osteoblast and osteoclast in regulation of blood
calcium.
Teaching ContentsCartilage
Cartilage is an organ,which is composed of cartilage tissue and perichondrium
(a layer of dense C. T. The cells in the inner layer of perichondrium can differentiate
into chondrocytes ).
1. Structure of cartilage tissue
The cartilage tissue is composed of cells and cartilage matrix (extracellular
matrix ). The cells are chondrocytes. The extracellular matrix consists of fibers and
ground substance.
(1). Chondrocytes:
Chondrocytes occupy small cavities in matrix which are termed cartilage
lacunae . Chondrocytes are small,flattened or oval in the periphery of cartilage They
are new born young cells . In the center of cartilage ,chondrocytes are large,oval
orrounded in shape and arranged in groups. A group of cells is termed isogenous
group which derived from a single chondrocyte. Chondrocyte contain a large,spherical
nucleus in the center. Nucleus has one or two nucleoli. The cytoplasm is weakly
basophilic. Under the E. M. the surface of chondrocyte is irregular and has some short
processes. It has abundant R. E. R and ribosome and Golgi complex.
Function:The chondrocytes can synthesize fiber and ground substance of the
cartilage tissue.
(2). Cartilage matrix :
The cartilage matrix is composed of fibers and ground substance. The chemical
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composition of the ground substance are water and proteoglycan ( 蛋白多糖 ) which
is composed of protein ,chondroitin sulfate and keratin sulfate . So the ground
substance is basophilic. There is much more chondroitin sulfate in the ground
substance around cartilage lacuna and show the dark blue colour in section. That is
termed cartilage capsule.
(3). fibers :
The fibers embeded in the ground substance . according to the different fiber in
the cartilage,the cartilage can be classified.
2. Classification
Cartilage can be classified into three kinds. They distribute in different part of
the body.
(1). Hyaline cartlage : It contains collagenous fibrils which is composed of collagen Ⅱ. It
mainly distributes in the trachea,bronchi,articular cartilage and rib cartilage .
(2). Elastic cartilage : It contains elastic fibers,mainly distribute in the auricle and
epiglottis.
(3). Fibrous cartilage : It contains the collagenous fiber,mainly distribute in the
intervertibral disc,symphysis pubis,articular cartilage disc.
Bone
Bone is also an organ,consist of osseous tissue,periosteum ,endosteum and
bone marrow .
1. Structure of osseous tissue :
osseous tissue consists of cells and extracellular matrix ( bone matrix ).
(1)Bone matrix : consists of organic component and inorganic component.
1). Organic component : It includes collagenous fibers ( collagen Ⅰ) and amorpous
substance that is proteoglycan. There are some
osteocalcin,osteoprotein,osteonectin and calbindin in the bone matrix . The
proteoglycan cement the parallel arranged collagenous fibers to form a bone
lamella.
2). Inorganic component :That mainly is calcium salt. mainly is hydroxyapatite crystal.
The bone matrix is arranged in layers or lamella. That is called bone lamella.
(2)cells:
1). Osteoprogenitor cells :They are young stem cells and have the mitotic
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potential. They have the ability to differentiate into mature bone cells. They are small
and spindle in shape. The nucleus is oval. The cytoplasm is weakly basophilic. They
locate in the endosteum,the inner layer of periosteum and vascular canals of compact
bone. They can differentiate into chondrocytes and osteoblasts.
2). Osteoblsts : They are much bigger than osteoprogenitor cells. They are
columnar, cuboidal or oval in shape with small processes. Nucleus is large,rounded.
The cytoplasm is basophilic. Under the E. M,there are a large amount of R. E.
R,developed Golgi complex in the cytoplasm.
Function :Osteoblast secrete fibers and organic ground substance and embed
themselves into the bone matrix,then they becme the osteocytes. This newly –
formed,uncalcified bone tissue is termed osteoid tissue.
3). Osteocytes (bone cells) : They are derived from osteoblasts. The osteocytes
ar embeded in bone matrix . They are flat,oval in shape with some fine long processes.
The nucleus is flat and stained dark. The cavities where the osteocytes occupied are
called bone lacunae. The space where the long processes occupied are called bone
canaliculi which radiate out from the lacunae.
4). Osteclast : osteoclast is large multinucleated cell. It is about 30-100 µm in
diameter. Usually there are 6-50 nuclei. The cytoplasm is acidophilic. Under the E.
M,The surface of the osteoclast facing the matrix has many microvilli It is termed
ruffled border under the L. M. There are many organelles in their
cytoplasm,mitochondria,lysosome,Golgi complex. Osteoclasts derived from many
monocytes.
2. Archetecture of long bone :
(1). Structure of compact bone :
It mainly distributes on the shaft of long bone (diaphysis). The compact bone is
also composed of lamellae . According to the pattern the lamellae arranged,the
lamellae can bedivided into three kinds :
1). Circumferential lamellae :
At the external and internal surface of the bone,there are several thin lamellae
running parallel with the surface and in concentric circle around the axis of the bone .
These are termed outer and inner circumferential lamellae. In general,the outer
circumferential lamellae are thicker and more regular than the inner lamellae. On the
lamellae there are many lacunae and canaliculi,that means there are many osteocytes
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in the lamellae.
2). Osteon or Haversian system :
Osteons locate between the outer and inner circumferential lamellae. They are
also termed Haversian system. Osteon is abot 3-5 mm in length and consists of two
parts:
(a). Central canal : It is a longitudinal channel ,located in the center of osteon. It
is also called Haversian canal . The canal contains blood vessels,nerve fibers and
small amount of connective tissue.
(b). Haversian lamellae : They are concentric lamellae surrounding the central
canal ,about 4-20 layers in number. There are many bone lacunae and bone canaliculi
in or between lamellae .
3). Interstitial lamellae :
These are irregular lamellae located among the osteons which are the remants
of Haversian systems partly destroyed during the reconstruction of the bone .
(2). The structure of spongy bone (epiphysis ):
The structure is very simple . It consists of trabeculae forming a spongy –like
network . The trabeculae is composed of some lamellae and osteocytes. There are red
bone marrow among the trabeculae.
(3). Periosteum and endosteum :
The periosteum is a special dense C. T which covers the outer surface of the
bone. It consist of two layers. The outer layer is dense and fibrous. The inner layer is
looser ,there are more cells,more blod vesselsOn stimulation or by fracture the cells
change into steoblasts in order to participate in the regeneration of bone tissue.
The endosteum is a thin layer of connective tissue lining the medullary
cavity,the central canals and covers the surface of the trabeculae. Also have some
cells which can differentiate into osteoblst. Both periosteum and endosteum play an
important roles in the grouth,protection,repair and constrution of bones.
Practice contentsL. M. Specimen : hyaline cartilage, elastic cartilage, fibro-cartilage, section
slide of bone , generation of long bone and flatten bone .
E. M. graph: chondrocyte, osteocyte. , osteoblast, osteoclast.
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Part III Blood and hemopoiesis
Learning objectives:1. Understand the structure , function and the normal quantity of different blood
cells, including erythrocyte, leukocyte and thrombocyte;
2. Distinguish different blood cells in the blood smear .
3. Know the structure and function of red bone marrow and yellow bone marrow.
4. Understand the basic conception of hemopoietic stem cell.
5. Know the basic role of morphologic change during the generation of blood cells.
Teaching contents:1. composing:Blood is a specialized from of connective tissue. It consists of blood
cells and blood plasma. The blood cells are formed elements and the plasma is
fluid substance.
blood cells(45 %):Red blood cells,white blood cells and blood platelets
plasma(55%):It constitutes of blood. It consists of water and dissolved inorganic salt,
proteins (fibrinogen, albulin, globulin), carbohydrate, lipid,
hormones,glucose and so on. When bleeding,the fibrinogen precipitates
to form a network of filaments,that is fibrin,the blood clotted. There is
some clear,yellowish fluid around the blood clot,that is called serum.
2. Erythrocytes(red blood cells)
(1) Shape:The clls are biconcave disc like. They show dark colour in the periphery and
light colour in the center when stained by H-E on the blood smear because it is
thick in periphery and thin in the center.
(2) Size:It is about 7. 5 µm in diameter.
(3) Number:It is about 4. 0-5. 5 million per cu mm in male (400-550 万 /mm3)
and 3. 5-5. 0 million per cu mm in female （350-500 万 /mm3 ） .
(4) Structure:They have no nucleus and organelle in mature erythrocytes. The
cytoplasm is homogeneous and filled with hemoglobin. Hemoglobin is a kind of
basic protein which has the ability to transport the oxygen and carbodioxide.
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The cell membrane is unit membrane. There is ABO blood type antigen on the
cell membrane. There is the erythrocyte membrane skeleton in the membrane.
(5) Reticulocytes:They are immature red blood cells. They just come into the blood
stream from bone marrow. normally they are about 0. 5-1. 5 % of total
erythrocytes in number in adult. it is about 3-6 % in new born baby. They are a
little larger than the R. B. C. When stained by brilliant cresyl blue They show a
fine blue network in cytoplasm,that is the remnants of ribosome.
3. Leukocytes(White blood cells)
(1) Normal number: 4000-10000/mm3 in normal human blood. They are
colourless,containing nuclei and spherical in shape.
(2) Classification:According to having the specific granules or not, the leukocytes can
be divided into two main types:
Granular leukocytes:subdivided into : neutrophil,Acidophil and Basophil.
Agranular leukocytes: subdivided into :Lymphocytes and Monocytes.
1). Neutrophilic granulocytes:
Normal percentage :They are the most numerous of total leukocytes. about 50-70 % of
total leukocytes.
size:They are 10-12 in diameter .
Structure:
Nucleus:The nucleus is highly polymorphonuclear (many lobed). It
usuallycontain 205 lobers connected by fine threads of chromatin,but
the three lobed is the most common. In routine smear,the nucleus
stained dark. The number of lobes increase with the age of the cells.
Cytoplasm : The cytoplasm is filled with fine granules which are surrounded by
membrane. The granules can be divided into two groups:
Specific granules : They are small granules and about 80 % of total
granules. The granules contain phagocytin and lysozyme.
Azurophilic granules:They are large granules and about 20 % of total
granules. They are lysosome containing acid phosphatase 、 acidic hydrolase
and peroxidase.
E. M : In addition to the granules,there are some organelles in the cytoplasm: very few
mitochondria, small R. E. R, undeveloped Golgi complex and great amount of
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glycogen.
Function :
chemotaxis :The neutrophils granulocytes can migrate towards the place of
injury or inflammation attracted to chemical substances liberated by
bacteria.
Phagocytosis: to killed the bacteria. So they have the defence function for the
body.
In acute inflammation ,the number of neutrophils increase greatly.
2). Acidophilic granulocytes:
normal percentage :They are about 0. 5-3 % of total leukoctes.
Size: They are largerthan neutrophils about 10-15 µm in diameter .
Structure :
Nucleus: It usually bilobed (has two lobes).
Cytoplasm: is filled with large acidophilic granules. Under the E. M,the
granules are oval in shape,each has a dense rectangle crystal core.
These granules are lysosome which contain histaminase( dissolve the
histamine),peroxidase ,sulfatase( inactivate the leukotriene) and four
kinds of cation protein ( kill the parasites) .
Function: as above.
The number of acidophils increase in certain allergic disease and parasitic
infection.
3). Basophilic granulocytes:
normal percentage : about 0-1 % of total leukocytes
size:They are the same size as neutrophils, about 10-12 µm in dimeter.
Structure :
Nucleus:They are also lobed nucleus. They are irregular. generally S-shaped.
Usually the outline is not distinct because of a lot of basophilic
granules overlying on it.
Cytoplasm:Contain large basophilic granules. These granules contain
heparin,histamine and eosinophil chemotactic factor. There is the
leukotrienein the ground substance of cytoplasm.
Function :They can take part in allergic reaction and release their granules
21
contains in response to the action of antigens.
4. lymphocytes:
Normal percentage : 25-30 % of total leukocytes.
Shape and size ;spherical, according todiameter,the lymphocytes can be divided
into:Small lymphocytes(6-8µm),Medium-sized lymphocytes(9-12µm) and Large
lymphocyte(13-20µm). The Large lymphocyte mainly in the lymph organs.
Structure :
Nucleus :They are spherical or oval . The nucleus is large with an identation. in
small lymphocyte ， The nucleus is so large that it fills nearly the
entire cell. The nucleus is surrounded by a narrow rim of cytoplasm (
a thin layer of cytoplasm) . Usually,in small lymphocytes,the nucleus
stain darkly because the chromatin packed densely.
Cytoplasm : The cytoplasm stained basophilic and contains some azurophilic
granules.
Classification: According to the origin and function,the lymphocytes can be classified
into three kinds:
Thymus dependant lymphocytes: T lymphocytes,75 %
Bone marrow dependant lymphocytes: B (Bursa)lymphocytes,10-15%→Plasma
cells
Nature killer lymphocytes: NK lymphocytes 10 %
5). monocytes:
Normal percentage: 3-8 %
Size:They are the largest cells of the blood,about 14-20 µm in diameter.
Structure :
Nucleus :The nucleus is oval,kidney or horseshoe shaped. The chromatin show
a fine delicate network so the nucleus is stained lightly.
Cytoplasm :It is faintly basophilic and also contains some azurophilic granules
which contain the peroxidase. Under the E. M,there are more R.E.R,
ewer ribosome,well developed Golgi
complex,microfilaments,microtubules
Function :They stay in blood only 12-48 hours and then migrate through the capillary
wall into C. T and become the macrophages.
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4. Blood platelet: also called thrombocytes.
Normal number :100-300 thousand /mm3 of blood.
Structure : They are 2-4 µm in diameter. The blood platelet are small cytoplasmic disc
that are the detached portion of megakaryocytes. In other words,they are
cell fragments. Megakaryocytes are located in bone marrow. Blood
platelets are rounded or ovoid,irregular in blood smear. They have no
nucleus. Each platelet has two regions :
The hyalomere : In the peripheral, there are numerous circumferential microtubules
and microfilaments to keep its shape.
The granulomere : It contains :
Specific granules : it is also called α granules,it is large,rounded, contain blood
platelet factor Ⅳ,platelet derived growth factor (PDGF),thrombospondin.
Dense granules :small,electron dense,contain，ADP,ATP, Ca++,adrenalin.
Canalicular system : open and dense canalicular system.
Function :play an important roles in hemostasis and clotting mechanism.
5. Development of blood cells ( hemopoiesis )
(1)Place :
At the end of second week of the development : during the embryonic stage,the
primitive blood cells ( that is the hemopoietic stem cells )occur in the wall of yolk sac.
From the second month of the development : the hemopoiesis occurs within
the liver,spleen and bone marrow.
After borth : The bone marrow is the main organ for hemopoiesis.
(2)Process :
Hemopoietic stem cell are the primitive cells of all kinds blood cells. They are
stem cells. They have the ability to differentiate into different blood cells. They are also
called multipotential hemopoietic stem cells. The hemopoietic stem cell can proliferate
and differentiate into committed stem cells in bone marrow which can proliferate and
differentiate only towards one kind of blood cells.
The maturation process of blood cells may be divided into three stage :
The problast stage
The blast stage
The mature stage
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(3)The law in the differentiation of erythrocytes:
Size : The size is reduction from large to small.
Nucleus : The nucleus become smaller and smaller,Finally lost it in mature
erythrocyte.
Cytoplasm : The cytoplasm increase gradually. The cytoplasm is deeply
basophilic at first,finally it become acidophilic.
Cell division : The ability of cell division gradually disappear.
Practice contents:
1. specimen: blood smear
2. Bone marrow and blood generation
3. specimen: bone marrow smear
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Chapter 4. Muscle tissue
Learning objectives:1. Understand the microstructure and function of three kinds of muscle tissues.
2. Understand the ultra-structure and different points between skeletal muscle and
cardiac muscle.
3. Know the ultra-structure of the smooth muscle.
Teaching contents:Introduction:
Muscular tissue mainly consists of muscle cells. There are some connective
tissue, blood vessels and nerve fiber between the muscle cells.
Muscle cell is a long, thin, thread-like cell. So the muscle cells are usually termed
muscle fiber.
There are some specific terms used to describe the muscle cell:
The cytoplasm is termed sarcoplasm.
The cell membrane is termed sarcolemma.
Smooth endoplasmic reticulum is termed sarcoplasmic reticulum.
Classification: According to the structure and function it can be divided into:
Skeletal muscle --- striated muscle
Cardiac muscle
Smooth muscle --- non striated muscle
Skeletal muscle
1. General structure of skeletal muscle fiber
(1)Size and shape: Muscle fiber is long, cylindrical in shape. The two ends are
rounded. It is about 1-40mm in length and 10-100µm in diameter.
(2)Structure: The skeletal muscle fiber is multinucleated cell. There are many distinct
cross-striations. The basement membrane surrounded the muscle fiber.
1). Nucleus:
The skeletal muscle fibers have numerous nuclei. They are ovoid in shape. The
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nuclei distribute peripherally just under the cell membrane (sarcolemma).
2). Sarcoplasm:
Sarcoplasm is filled with long, parallel-arranged myofibrils. Besides myofibils,
there are a lot of organelles in sarcoplasm. There are numerous mitochondria, small
Golgi complex, some lipid droplets, glycogen and myoglobin.
Myofibril is about 1-2µm in diameter. In longitudinal section, each myofibril
show regular cross-striations. Those are dark (A) and light (I) bands. In cross section,
the myofibrils appear as dots with sarcoplasm around them. Dark band is also called A
band. Light band is also called I band.
In the center of A band, there is a H band, stained less dark.
In the center of H band, there is a dark M line.
In the center of I band, there is a dark Z line.
Usually, A band is about 1. 5um long and I band is about 0. 8-2. 0um long.
Sarcomere: Sarcomere is the basic structural and functional unit of each myofibril.
The segment of myofibril between two adjacent Z line is called a sarcomere. Its
length is about: 1/2 I + A +1/2 I. About 1. 5 – 3. 5µm.
2. Ultrastructure of skeletal muscle fiber
(1)Myofibril:Under the E. M. , myofibrils are composed of myofilaments. There are two
types of myofilaments: thick myofilaments and thin myofilaments.
1). Thick myofilament:
It is about 1. 5µm long and 15nm in diameter, located in A band. It is composed of
a bundle of parallel myosin molecules. Myosin molecule has a bean sprouts shape. It
has a shaft and a head. The head just like two pieces of bean sprout. The shaft of all
myosin molecules are arranged toward the M line and the head protruding from the
bundle as the cross bridge. The heads possess the adenosine triphosphatase
(ATPase). The head also has a point (a binding site) to combine with the actin
molecule.
2). Thin myofilament:
It is about 1. 0µm long and 5nm in diameter. Itˊs one end attached to the Z line
and the other end insert into A band and terminate at the outside of H band. It is
composed of three kinds of protein: actin, tropomyosin and troponin.
3)Actin:
It is the main part of the thin myofilament, which consists of two strands of
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globular subunits. Each globular subunit has a binding site to combine with myosin.
4)Tropomyosin:
Tropomyosin molecule is a long, slender protein molecule that is composed of two
spiral chains of polypeptide. Tropomyosin lies in the groove between two strands of
actin.
5)Troponin: Troponin is composed of three globular subunits:
C-subunit: combine with Ca2+
T-subunit: combine with tropomyosin
I-subunit: inhibit the actin to combine with myosin
(2)Sarcolemma and transverse tubule
Sarcolemma invaginate vertically into the cell to form the transverse tubule. The
transverse tubule branch and encircle each myofibril called T tubule. In human
body the T tubule is at A-I junction level.
Function: Nervous impulse on the surface sarcolemma can be carried to the interior of
the fiber by T tubule rapidly.
(3)Sarcoplasmic reticulum
1). Sarcoplasmic reticulum is a special type of the smooth endoplasmic reticulum of
muscle fiber. The S. E. R. are longitudinal tubular system, located between two
transverse tubules, also surround each myofibril. It is called longitudinal tubule (L
tubule). At the ends of L tubules, the tubules enlarged and connected to form a large
terminal cisternae. It closed to the T tubule. There is a pair of cisternae at each side of
T tubule.
2)Triad: The two terminal cisternae together with the central T tubule form a triad at A-I
junction level.
3)Function: The tubule can store the calcium ions. They can regulate the
concentration of calcium ions in sarcoplasm.
3. Mechanism of contraction
The mechanism of skeletal muscle fiber contraction is “sliding filament mechanism”.
When muscle fiber contract a change occurs in relative position of two myofilaments.
The thin filaments slide past the thick filaments, the ends of thin filaments being drawn
inward toward the M line and the H band become shorter, finally vanish. At the same
time, I band becomes shorter and the sarcomere becomes shorter, but the length of A
band has not any change.
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Cardiac muscle
1. General structure of cardiac muscle fiber
(1)Size and shape:
It is about 80-150µm in length and 10-20µm in diameter. Cardiac muscle fiber is
short, cylindrical in shape. It branches at the end and associated with each other.
(2)Structure:
They also have many cross striations, A bands and I bands. They also have Z
line in the center of I band, but the striations are not as distinct as that in skeletal
muscle fiber.
1). Intercalated disc:
The most special structure in cardiac muscle fiber is intercalated discs, which is
the adhesive area between two adjacent cells. In longitudinal section, it is a dark,
zigzag or step-like line crossing the fiber. Intercalated disc is the characteristic
structure of cardiac muscle fiber.
2). Nucleus:
Usually, it has a single, ovoid nucleus in the center of sarcoplasm. There is
abundant sarcoplasm in the both ends of nucleus, in the section, that region stained
light.
3). Sarcoplasm: Sarcoplasm is very abundant. There are much more mitochondria in
sarcoplasm. Besides, there are some small Golgi complex, lipid droplet and lipofuscin
pigments, glycogen. Functionally, there are many myofilaments in sarcoplasm.
2. Ultrastructure of cardiac muscle fiber
We mainly study some difference from the skeletal muscle fiber.
(1)They also have myofibrils, but they are irregular. Some of the myofibrils are thick
and some are thin.
(2)They have T tubules, but they located at Z line level.
(3)They have L tubules also, but not as developed as in skeletal muscle. The L tubules
enlarge and connect to form terminal cisternae only at one end. Hence, they only
have diad, not triad.
(4)Intercalated discs are the specialized cell junctions at Z line level. Under the E. M. ,
they have transverse and longitudinal portion. In transverse regions, they are
desmosome and intermediate junctions. In longitudinal regions, they are gap
junctions.
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(5)The atrial muscle fiber can secrete the atrial natriuretic polypeptide (ANP).
Smooth muscle
1. General structure of smooth muscle fiber
Smooth muscle mainly consists of smooth muscle fibers. Smooth muscle mainly
distribute in visceral organs to make up the wall of hollow viscera and the wall of ducts
and vessels.
(1)Size and shape: Smooth muscle fibers are elongated, spindle-shaped cells. There is
a marked variation in length and diameter in different parts of the body. In
general, they are about 200µm long and 8um in diameter. In small blood vessels, it
is about 20µm long, but in pregnant uterus, it is about 500µm long.
(2)Structure: They have no transverse striations. Normally the cells are gathered into
dense sheets (layers) or bands. Within the sheets and bands, smooth muscle
cells are densely packed together and narrow portion of one elongated nucleus in
the central and broadest portion of each cell. The nucleus often shows a screwy
shape because of the fiber contracting. The cytoplasm is acidophilic in H. E.
routine section.
2. Ultrastructure of smooth muscle fiber
(1)They have myofilaments in cytoplasm, but we cannot see the myofiberl in
cytoplasm. There are three kinds of myofilaments:
Thick myofilament: It is composed of myosin.
Thin myofilament: It is composed of actin.
Intermediate myofilaments: They expand from dense body to dense patch (dense
area). The intermediate myofilaments together with the dense patches and
dense bodies constitute a cytoskeleton of the cell. there is no sarcomere.
(2)Electron-dense area, termed dense patches, are scattered on the inner surface of the
sarcolemma. They are equal to the Z line in skeletal muscle fiber.
(3)Dense bodies are scattered throughout the cytoplasm. It is small spindle body. The
thin and intermediatemyofilaments attached to the spindle body.
(4)They have no the T tubule system, but they have many caveolae formed by
sarcolemma. They are equal to the transverse tubule in skeletal muscle fiber.
They can transmit the nervous impulse.
(5)The sarcoplasmic reticulum is undeveloped and close to the caveola.
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(6)There is no myofilament in the juxtanuclear sarcoplasm, but there are Golgi
complex, a few mitochondria, free ribosomes, R. E. R. and glycogen in cytoplasm.
Practice contents:L. M. specimen: the longitudinal and cross sections of skeletal, cardiac and smooth
muscle.
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Chapter 5 Nerve Tissue
Learning objectives:1. Understand the basic structure of nerve tissue; the structure and function of nerve
cell and neuroglia.
2. Understand the ultra-structure and classification of the synapse.
3. Understand the structure and classification of nerve fibers.
Teaching contents:General characteristics
Nervous tissue is highly differentiated tissue and is principle element of the
nervous system and consists of two classes of cells:
Nervous cells(neurons): The neuron is the structural and functional cellular
tissue of the nervous tissue. They can react to mechanical and chemical stimuli and
conduct nervous impulses.
Neuroglial cells: Usually, they are smaller than neurons, however, the number of
former is about 10 times of later. They can support, protect, nourish and insulate
neurons, although they have no the function of transmission of nervous impulses.
Neurons1. Structure of neuron: The neuron consist of two parts: soma and processes.
(1)Soma
Shape and size: The soma of neuron may be spherical, pyramidal, stellate, or irregular
in shape. The soma varies greatly in size. They may be as small as 5-6µm,or as
large as150µm in diameter. soma is the center of metabolism and nutrition in
neuron.
Structure of soma: It also has cell membrane, nucleus and cytoplasma, just like other
cells.
1). Nucleus:It is a large, spherical and central located one with a large, distinct
nucleolus. There is a little amount of the heterochromatin. Therefore the
nucleus appears empty and pale under the L. M.
2). Cytoplasm: It contains well-developed Golgi complex, abundant mitochondria,
lysosome, some inclusions, such as lipofuscin and two characteristic
31
structures:
Nissl body:
It is also called chromophil substance. It is basophilic and easy to be
stained by basic dyes. They appear as blue granules or patches in H. E.
stained. They are present throughout the soma and dendrites, but absent from
the axon hillock and axons. In the motor neurons of spinal cord, they are more
abundant.
E. M. : Nissl body is composed of well-developed R. E. R and ribosomes
which indicates the Nissl body are the main place for synthesis protein.
Neurofibril
They are fine, black, filament-like lines in silver stained. They crisscross to
form a network and extend into axon and dendrites.
E. M. : Neurofibril consists of microtubules and neurofilament. They
support the neurons as a cell skeleton and transport some substances.
3). Cell membrane: Most of the cell membrane,except the membrane in synapse,is unit
membrane. It is a sensitive excitable one. There are many receptors and ions
passageway on it. So it can react to stimuli, produce and conduct nervous
impulses.
2. Process: There are two types of processes: dendrites and axons.
(1). Dendrites: They arise from soma and often branch like trees. They are usually
shorter and thicker than axons. On their surface, there are numerous
fine projections called dendritic spines.
Structure: The structure of dendrites is similar to that of soma. Its cytoplasm
contains Nissl body, neurofibril and mitochondria, but no Golgi complex.
Function: They can receive the nervous impulses from other neurons, transmit the
information to the soma. At the same time, dendrites and dendritic
spines increase the surface of neurons.
(2). Axon: Axon arise from the axon hillock, a small conical elevation of soma. Usually,
each neuron only has one axon. In general, axon are longer and shorter
than dendrites. They do not branch or only have a few branches.
Structure:1). Axolemma: The membrane enclosing the axon is termed axolemma.
2). Axoplasm: The cytoplasm of the axon. It contains mitochondria, S. E.
R. , neurofibril, but no Nissl body and Golgi complex.
32
3). Axon terminal: The axon terminate in the form of rounded
enlargement called axon terminal or axon button.
4). Axonal transport: Experiments have proved that materials are
conveyed along the axon from the soma to the axon terminals or in the
opposite direction.
Function: axon conduct nervous impulses away from soma to another neurons
or affecters.
(2)Classification of neurons
1). According to the number of their processes : It is the most common method.
Pseudounipolar neurons: With only one process which soon divides into two
branches in a T-shape.
Biopolar neurons: two processes: one axon and one dendrite.
Multipolar neurons: with more than two processes.
2). According to the function of the neurons:
Sensory neurons: They are also called afferent neurons, receive the sensory
stimuli and transmit sensory nervous impulses to the central
nervous system.
Motor neurons: They are also called efferent neurons, conduct motor nervous
impulses to effecters.
Interneurons: They connect afferent and efferent neurons to form functional
circuit.
3). According to the neurotransmitter the neurons secreted
Cholinergic neurons
Aminergic neurons
Peptidergic neurons
Aminoacidergic neurons
Synapse1. Concept: Synapse is a specialized cell junction (place) between neuron and neuron
or between neuron and nonneuron (such as muscle cell, glandular cell).
2. Classification: accoding to the nature of synapse
chemical synapse: most synapse
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electrical synapse: rarely in the nervous system
3. chemical synapse:In the chemical synapses, the transmission of nerve impulses is
mediated by chemical substances which is called neurotransmitters.
Synapses may occur between any part of two neurons. More often, they
are formed between axon and dendrite, called axodendritic synapses or
axon and soma, called axosomatic synapses.
Struture:
L. M: The axonal terminals appear as rounded enlargement to contact with the
dendrite or soma of another neuron. The enlarged axonal terminals are
termed terminal button or synaptic button.
E. M. :It consists of three parts: presynaptic element, synaptic cleft and
postsynaptic element.
(1) Presynaptic element: It is axonal terminal enlargment. It contains:
Synaptic vesicles: They are characteristic structure of presynaptic
element. They are membrane-coated vesicles. Neurotransmitters
are store in these vesicles.
Mitochondria
Smooth endoplasmic reticulum/S. E. R
Microtubules
Microfilaments
At the synaptic contact, the axon plasmalemma becomes thickened and
dense, termed the presynaptic membrane.
(2) Synaptic cleft:It is the extracellular space between the presynaptic
membrane and the postsynaptic membrane. It is about 15-30nm.
(3) Post synaptic element:It is the plasmalemma at the contact point on the
receiving neurons. Most of them are on dendrites or cell bodies. Like
presynaptic membrane, post synaptic membranes are thickened. There are
some specific receptor molecules in the postsynaptic membrane.
When the nerve impulse reaches the presynaptic element, the synaptic
vesicles fuse with the presynaptic membrane and discharge the neurotransmitters into
the synaptic cleft. The neurotransmitters then diffuse across the cleft and combine
with the specific receptor in the postsynaptic membrane. The nerve impulses transmit
from one neuron to anther only in one direction.
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4. Electrical synapse
Structurally, electrical synapses are equivalent to gap junctions between
epithelial cells .
The trasmission needn’t the neurotransmittors and there is no synaptic vesicle.
Current spreads from one neuron to an adjoining one directly in both directions.
Nerve fiberNerve fiber is composed of an axon and a surrounding neuroglia
(oligodendrocytes in centraland the Schwann cells in peripheral nerve
system). There are two types of nerve fibers in the central and peripheral
nervous system : myelinated and nonmyelinated nerve fibers .
1. myelinated nerve fibers: is composed of axon and myelin sheath.
(1)Structure: 1)The axon is in the center of the nerve fibers which enclosed by
myelin sheath.
2)The myelin sheath is formed by the cell membrane of Schwann
twining around the axon
L. M. :the myelin sheath are segmental arranged just like lotus roots. The
constricted region between adjacent segments is termed Ranvier node. At
such nodes, the axons are exposed. Each segment between two adjacent
Ranvier nodes is termed internode. In routine section, the lipids of myelin
sheath are dissolved out only left the protein. The protein is fixed and
showed a spongy framework in the sheath (which is also termed
neurokeratin network ).
In the preparation stained by osmic acid, the myelin sheath is black,
we can see several oblique incisures, termed Schmidt-Lanterman incisures
or incisures of myelin.
E. M. :the myelin sheath is seen as a series of concentrically arranged light and
dark lamellae.
Functions of the myelin sheath
It provides an insulation layer around the axon to speed up impulse
conduction. Nerve impulses jump from one node to the next, so the speed is
very fast.
35
2. nonmyelinated nerve fibers:
Nonmyelinated nerve fibers are composed of an axon and a surrounding
neuroglia where is no myelin sheath and Ranvier node. In the peripheral nervous
system, the Schwann cell has several grooves in which the axons are embedded.
The impulse conduction occurs along the axon, rather than jumping across nodes.
The speed is slow.
Nerve endings
1. Concept: peripheral nerve fiber ends in other tissue or organ to form a specialized
structure. termed nerve endings.
2. Classification: according to the function,nerve endings may be divided into two
groups :sensory nerve endings and motor nerve endings.
3. Sensory nerve ending ( afferent nerve ending,receptors ):
(1). Free nerve endings
Location: in epidermis, cornea, tunica serosa, muscle tissue and connective
tissue.
Structure: The terminals lost their myelin sheath. The naked nerve fibers
branch to distribute among the cells.
Function: receive the temperature and pain stimuli
(2). Encapsulated nerve endings: in this group of endings, there is a special
connective tissue capsule surrounds the nerve endings.
1). tactile corpuscle: also called Meissner’corpuscle
Location: in the dermal papillae in the tips of fingers and toes.
Structure:They are oval bodies. There are many flattened cells in the corpuscle
arranged horizontal. The nerve fiber loses it’s myelin sheath, enter
the corpuscle and branch around the cells.
Function: touch receptor
2). lamellar corpuscle: also called Pacini’corpuscle
Location: in the hypodermis, mesentery and pancreas.
Structure: They are large, ovoid structure. In the center, there is a homogenous
bulb. Many concentric lamellae of flattened cells surround the inner
bulb. The nerve fiber loses myelin sheath, enter the corpuscle and
36
end in the inner bulb
Function: pressure and vibration receptor
3). muscular spindles:
Location: in the skeletal muscle
Structure: They are fusiform structure. They are formed by a few small skeletal
muscle fibers, termed intrafusal muscle fibers. The nuclei of those
fibers gather in the middle part. The sensory nerve fibers lose
myelin sheath and enter the spindle, twining the middle part of
intrafusal muscle fibers. Besides the sensory nerve fibers, there are
some small motor nerve fibers enter into the spindle to form the
motor end plate.
Function: mechano-receptor , can detect the change in muscle length
4. Motor nerve ending ( efferent nerve ending,effector ):
(1). Motor end plate
Location: in the skeletal muscle
Structure: That is somatic motor nerve ending. The somatic motor nerve fibers
enter skeletal muscles and lose myelin sheath, then branch into the
claw-shape branches with the terminal swellings. The swelling
terminal branches approach the muscle fibers to form the motor end
plates. Under the E. M. , the terminal axon is expanded and contains
mitochondria and numerous synaptic vesicles, in which the
neurotransmitter acetylcholine is stored. The membrane of axon
terminal is presynaptic membrane and the sarcolemma of the
muscle fiber is postsynaptic membrane. The sarcolemma is highly
convoluted. There is a synaptic cleft between two membranes about
40-60 nm in width. Actually, that is myoneural junction.
Function: conduct nervous impulses
(2). Visceral motor nerve finding
Location: in the smooth, cardiac muscle and glands.
Structure: The axon terminal of thin unmyelinated nerve fiber branch and
expand like a string of beads(varicosity), filled with synaptic
vesicles, to approach the muscle cells or glandular cells. Actually,
that is another synapse.
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Function: conduct nervous impulses
Practice contents:L. M. specimen:nerve cell,synapse,neuroglia,myelinated nerve fiber,unmyelinated
nerve fiber.
Chapter 6 Nerve System(individual study)
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Chapter 7 Circulatory System
Learning objectives:1. Know the general structure of walls of circulatory system.
2. Understand the microstructure of capillary, the ultra-structure of several kinds of
capillary and its function.
3. Understand the structure and function of large artery,medium-sized artery and
small artery;know the histological change of hypertrophic tunica intima of artery.
4. Know the general structure of vein.
5. Know the structure and function of every segment of microcirculatory vessel.
6. Understand the structure of heart.
7. Know the general structure of the wall of lymphatic vessel.
Teaching contents:It is divided into two major components according to the circulating
fluid in the tubes: the lymph vascular system and the cardiovascular system.
Capillaries1. structure of capillaries diameter:6-8um (1)endothelium: 1-3 cells (2)basement membrane (3)pericyte(周 C):irregular and branched cells, be encircled by basal lamina, can
differentiate into endothelium and fibroblasts2. classification: In E. M according to the structure of endothelium and basement
membrane. (1). Continuous capillary
structure: 1)there are many plasmalemmal vesicles in the cytoplasm of endothelial cells. size:60-70nm. function:transport substances of metabolism.
2)intercellular space :tight junction and desmosome3)basement membrane: continuous
distribution: C. T; muscular T; lung; brain(2). Fenestrated capillary
structure:1)there are many pores or fenestrae within the attenuated endothelial cytoplasm. The poress are usually closed by a diaphragm which is thinner than an unit membrane. size:60-80nm.
2) intercellular space: as same as that of the continuous type. 3) basement membrane: continuous
distribution: gastrointestinal tunica mucosa; renal glomerulus; some endocrine gland
(3). Sinusoidstructure: 1)endothelium have pores too. the sinusoid is irregular in shape and
much wider in diameter. 2)intercellular space: wide gaps3)basement membrane: continuous or incomplete.
distribution:liver; spleen; bone marrow; certain endocrine gland
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Arteries
The structure and function of arteries change as their diameters decrease. The structure of medium-sized artery is typical,take it for instance.
1. structure of medium-sized arteries (1) tunica intima 1)endothelium 2)subendothelial layer: C. T collegenous fibers, elastic fibers,a few smooth muscle
cells 3)internal elastic membrane: is composed of elastin as a definite limit between the
tunica intima and the tunica media. looked like a bright refractile, wave-like band in the section
(2)tunica media: is the thickest layer,mainly composed of 10-40 layers of circular
smoothmuscle cells. so it also termed muscular arteries or distributing arteries. between muscle fibres : collegenous fibers and elastic fibres which produced by smooth muscle cells but no fibroblast.
(3)tunica adventitia1)external elastic membrane: a layer or several layes. 2)loose C. T:collagenous fibres,elastic fibres,blood or lymph vesseles, N. F, fat
cells. 2. large ateriesfeatures:(1) the internal and external elastic membranes are not distinctive.
(2) tunica media: is mainly composed of 40-70 layers of circular elastic membranes. is also termed elastic artery.
3. small arteries: 0. 3mm < d < 1mm is also termed muscular artery. Endothelium+several layers of smooth muscle
4. arteriole: d < 0. 3mmVeins
features:1. larger diameter, thinner walls, irregular lumen, less elastic. 2. the tunica media is thinner. the tunica adventitia is thicker than that of arteries. It is the thickest layer of a vein. there are relatively less smooth muscle and more C. T. the boundaries between the three tunicae of a vein's wall aren't clear.
3. semilunar-like valves: prevent back-flow of the blood. Heart
organization of the heart including the heart wall,valves and conducting system1. heart wall: consist of three main layers(1). endocardium
1). endothelium2). subendothelium: a thin-dense sheet of C. T 3). subendocardial layer: loose C. T containing conduting system of the heart
nerves, blood vessels. the subendocardial layer isn't present in the papillary muscles and the chordae tendineae.
(2). myocardium:1) mainly composed of cardiac muscle. containing rich capillaries2) the myocardium is the thinnest in the atria,thicker in the right ventricle and the
thickest in the left ventricle. the muscle fibres are arranged roughly in the inner longitudinal layer, the middle circular layer and the outer oblique layer.
3) the atrial and ventricular muscles are separated from each other by an atrioventricular fibrous annulus. composed of dense C. T: the atria and ventricles contract asynchronously.
(3). epicardium1). is the visceral layer of the pericardium2). it is a serous membrane : C. T ＋ mesothelium
2. cardiac valve:(1)formed by folding of endocardium
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(2)structure: endothelium on both sides dense C. T: forms the core of the valves(3)function: prevent back-flow of the blood3. conducting system(1)composition
1)sinoatrial node(SA node):lies in the subepicardial position near the juntion of the superior vena cava and the right atrium
2)atrioventricular node(AV node)3)atrioventricular bundle:are located beneath the subendocardial layer.
conducting system is composed of the special cardiac muscular cells. The types of cells:P-cell (pacemaker cell),transitional cell and purkinje fiber. (2). P-cells
distribution: almost exclusively in the SA node and AV node. particularly in the central part of the SA node.
function: make impulse(3). Transitional cells
distribution: SA node and AV node. in the AV node, they constitute the principal cell-type. they extend to the periphery of the nodes and link P-cells to ordinary cardiac muscular-cells
function: conduct impulse(4). purkinje fibres
distribution: are the principal cell-type in the AV bundle and bundle branches. form the network of purkinje fibres
function: transmit impulse to working myocardial cells 4. AVP (atrial natriuretic polypeptide) or (cardionatrin)
In the cytoplasm of the atrial muscle fibres, there are some granules which termed specific atrial granules. In E. M, the granules are spherical, various in size, membrane- bound, and electron-dense. the granules store the hormone which is made up of 21- 33 amino acid polypeptide. the hormone is termed cardionatrin.
Function of ANP:natriureic function to relax blood vessels and decrease blood
pressure
Practice contents:L. M. specimen:medium-sized artery and vein,large artery and vein,small artery and
vein,heart.
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Chapter 8 Immune System
Learning objectives:1. Know the constitution of immune system and the conception of immunity.
2. Understand the classification of lymphocytes and the role of every kind of
lymphocyte in immune reponse.
3. Understand the role of macrophage in immune reponse;the constitution and
distribution of mononuclear phagocyte system.
4. Understand the structure and function of central lymphoid tissue and periphery
lymphoid tissue.
5. Know the structure and function of thymus.
6. Understand the general structure and function of lymph node and spleen;know the
structural change of lymph node and spleen in different immune response.
Teaching contents:Immune organ, immune tissue, immune cells
FUNCTION 1. Immunologic defense function
2. Immunologic surveillance function
LYMPHOCYTE
1. Thymus dependent lymphocyte①Helper T cell, Th ,CD4, cluster of differentiation,
increase immune response,acquired immune deficiency syndrome; ②Suppressor T
cell, Ts, regulate function of other T and B cell;③Cytotoxic T cell, kill the target cell
directly, fatal kiss; ④memory T cell, Tm
2. Bone marrow dependent lymphocyte: stimulated by antigen proliferating and
differentiation plasma cell→Ig→mediate toxin, suppress metabolism of target cell ,
memory B cell, Bm
3. Natural killer cell: kill the target cell directly
LYMPHOID TISSUE
Reticular tissue (framework) + immune cells
1. Diffuse lymphoid tissue: postcapillary venule
2. Lymphoid nodule:
primary lymphoid nodule: no germinal center
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secondary lymphoid nodule: germinal center
LYMPHOID ORGAN
1. Thymus
Capsule, interlobular septum
(1)Cortex ：epithelial reticular cell + thymocyte
1) epithelial reticular cell: ①subcapsular epithelial cell: thymosin and thymopoietin—
development of thymocyte; ②interdigitating dendritic cell—positive selection
2) Thymocyte: T cells in various development period
(2)Medulla: ①medullary epithelial cell—thymosin②thymic corpuscle epithelial cell
(3)Blood-Thymus Barrier: ①continuous capillary, ②endoepithelial basement
membrane, ③CT surrounding blood vessel, ④epithelial basement membrane,
⑤processes of thymic epithelial cell
Function: prevent antigen of blood from reaching the thymus; maintain the stability of
the microenviroment
Function of thymus: developing and maturing of T cell; secrete thymic hormone
2. Lymph Nodes
Capsule, trabecula
(1) Cortex
1) superfacial cortex: lymphatic nodule—germinal center—cap, light zone, dark zone
2) paracortex zone: diffuse lymphoid tissue, thymus dependent area
3) cortical sinus: subcapsular sinus, peritrabecular sinus
(2) Medulla
1) medullary cord
2) medullary sinus
(3) Function of lymph node: ①lymph filtration, ②immune response
3. Spleen
(1) Capsule: thicker, smooth muscle, mesothelium
(2) White pulp:
1) periarterial lymphatic sheath: diffuse lymphoid tissue surrounding the central
artery, corresponding to paracortex zone, no postcapillary venule
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2) splenic corpuscle: lymphatic nodule
3) marginal zone: surrounding the white pulp, the border between white pulp and red
pulp
4) red pulp: splenic cord, splenic sinus
(3)Function of spleen: ①immune response, ②store of blood, ③produce blood cells in
fetal life, ④destroy aged red cells
Practice contents:L. M. specimen:thymus,lymph node,spleen.
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Chapter 9 Digestive System
Part I Digestive Tract
Learning Objectives1, understand the basic structure of digestive tract and structure and function of every
segment.
2, know the digestive and immunity.
3, know the distribution, main type and function of endocrine cells of digestive tract.
Teaching Contents
General structure of digestive tract
1. Mucosa
(1) Epithelium: ①stratified squamous epithelium—protection
② simple columnar epithelium—absorption
(2) Lamina propria: LCT
(3) Muscularis mucosa: smooth muscle; circularly arranged inner
layer,longitudinally arranged outer layer
2. Submucosa: LCT
3. Muscularis: an inner layer of circularly arranged muscle fiber; an outer layer
of longitudinally arranged muscle fiber
4. Adventitia: Fibrosa—CT; Serosa—CT+mesothelium
Esophagus
Several longitudinal folds
1. Mucosa
(1) Nonkeratinized stratified squamous epithelium
(2) Muscularis—longitudinal muscular fiber
2. Submucosa: mucous gland
3. Muscularis: upper one third—skeletal muscle
middle one third—smooth muscle and skeletal muscle
lower one third—smooth muscle
4. Fibrosa
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Stomach
1. Mucosa gastric area; gastric pit
(1) Epithelium: surface mucous cell
(2) Lamina propria:
1) Fundic gland
① Chief cell: zymogenic cell, most numerous, basal part,
LM: columnar, basophilic, prominent secretory granules in the apical part;
EM: abundant RER, prominent Golgi complex
Function : Pepsinogen HCl pepsin
② Parietsl Cell: oxyntic cell, upper half of part
LM: acidophilic, pyramidal
EM: intracellular secretory canaliculus, tubulovesicular system,
abundantmitochondria, less RER and Golgi complex
Function : HCl and intric factor---vitamin B12
③Mucous neck cell: neck, supranuclear part of the cells contain prominent
granules
④Stem cell: multiply to replace other cells
⑤Endocrine cells
2) Cardiac gland: mucous gland
3) Pyloric gland: mucous gland
(3) Mucularis mucosa
2. Submucosa
3. Muscularis: 3 layers, from inside to outside, oblique, circular and longitudinal
4. Adventitia: Serosa
Small Intestine
Duodenum, jejunum, ileum
Increase the surface area: circular fold—mucosa + submucosa; villi—Ct core covered
by surface epithelium; microvilli
1. Mucosa
(1) Epithelium: columnar cells, goblet cells; endocrine cells
(2) Lamina propria: intestinal gland—stem cell;
Paneth cell: only found in the deeper part, prominent acidophilic secretary
granules--defensin
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2. Submucosa: deodeunal gland
Colon
1. Mucosa: numerous crescent-shaped folds, no villi, no Paneth cells,
numerous goblet cells, numerous tubular glands
2. Submucosa: often contain fat cells
3. Muscularis: taenia coli—3 thick bands
4. Serosa: appendices epiploicae
Endocrine cells
Argentaffin cells, basal granular cells
Practice ContentsL. M. specimen: pharynx, esophagus, gastric fundus, pyloric portion, duodenum,
jejunum, ileum, colon, appendix, endocrine cells of digestive tract.
E. M. graph: chief cell, parietal cell, small intestinal epithelium, endocrine cell of
digestive tract.
Part II Digestive GlandsLearning Objectives1, understand the structure and function of liver, the structure of hepatic lobule and
portal area.
2, understand the ultrastructure and function of hepatocyte, hepatic sinusoid.
3, understand the features of blood circulation of liver and their relationship with
hepatic function.
4, know the structure of gall, bladder and bile duct.
5. understand the structure and function of pancreas.
6. know the ultrastructure of pancreas islet cells and its hormone.
Teaching ContentsSalivary Gland
1. General structure
(1)Acinus
1) Serous acinus: pyramidal, contains secretary granules (zymogen granules) in
apical cytoplasm, abundant RER, well developed Golgi complex
2) Mucous acinus: columnar, mucinogen granules
3) Mixed acinus: serous cells arranged in demilunes
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(2)Duct
1) Intercalated duct: simple cubodial or squamous
2) Striated duct: secretary duct, simple columnar cell, deep infoldings of the
basal parts, mitochondria, regulating the water and electrolyte
3) Interlobular duct:
2. Features of 3 salivary glands
(1)Parotid gland: serous gland, long intercalated duct, short striated duct
(2)Submandibular gland: mixed gland, more serous acinus, fewer mucous and
mixed acini
(3)Sublingual gland: mixed gland, more mucous, mixed acini and demilunes, no
intercalated duct
Pancreas capsule: thin C. T, lobulesparenchyma: exocrine pancreas
acinus--secrete pancreatic fluidducts
endocrine panereas: pancreatic islets1. exocrine pancreas:
(1)Acini: serous glandular cell. contain abundent acidophilic zymogen granules. function: secrete a large number of digestive enzymescentroacinar cells: small, light- staining squemous or cubic cells
which are the cells extended from the intercalated duct(2)Duct: intercalated ducts→intralobular ducts→interlobular ducts
→pancreatic ducts→opens into a recess of the duodenal lumen2. endocrine pancreas:
pancreas islet: the endocrine cells of the pancreas are grouped into small spherical clusters scattered among the exocrine acini.
four different cell-types can be distinguished by special staining(1). A-cell: 20％,periphery,glucagons,increase the rate of conversion of liver
glycogen to glucose. Raise blood sugar level. (2). B-cell: 70%,center,insulin,increas the utilisation of glucose and glycogenesis.
decrease blood sugar level. (3). D-cell: 5％,scattered,somatostatin,adjust the release of glucagon and insulin. (4). PP-cell: a few scattered pancreatic polypeptide.
Liverstructure capsule: cense C.T + mesotheliumhepatic lobule: central vein,hepatic plates,hepatic sinusoid,
perisinusoidal space and bile canaliculi. portal area:interlobular A,interlobular V and interlobular bile duct.
1. hepatic lobule: It is the basic structural and functional unit of liver(1). central vein: lie in the centre of the hepatic lobule. continuous with
sinusoids. (2). hepatic plates: consists of a row of closely- packed hepatocytes. the
hepatic plates are arranged radially around the central veinHepatocytes:
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L. M: shape: polygonal cell, clear boundarynucleus: spherical. 1-2cytoplasm: eosinophilic
E. M: many organelles in the cytoplasm1) Mitochondria: 1000-2000. major source of energy2)Golgi complexes: distributed around the nucleus especially near bile
canaliculi. is associated with synthesis of protein and secretion of bile. 3) R. E. R: the center of generating many kinds of protein4) S. E. R: is involved in the formation of bile, the metabolism of lipid hormone
and detoxification.5) Lysosomes: is a cellular digestive organelle,is associated with the
metabolism of bile pigment6)Microbodies: contain catalase and oxidative enzymes. is involves in the
detoxification. 7) inclusion: glycogen particles, lipid droplets and pigment. etc.
(3). sinusoidsform an extensive spongework between the hepatic plates and radiate from the
central vein in a lobule. the lining of sinusoid consists of:1) endothelial cell2) Kupffer cell: skellate-shaped, dispersed among the endothelial cells or in
sinusoid. belong to mononuclear phagocytic system. (4). perisinusoidal space
1)concept: under the E. M, it is a marrow interstice between the endothelium of sinusoid and hepatocytes. is full of plasma. It is the place where exchanges of metabolic substance between the liver and the plasma occur.
2)perisinusoidal space contain:reticular fibersplasmafat-storing cell: irregular, flat, has processes storing fat droplets and VitA.
(5). bile canaliculiconcept: cell membranes of adjancent hepatocytes invaginte partly into cytoplasm
, and form the bile canaliculi. The canaliculi runs between hepatic plates to the periphery of the lobule. also radiate from the central vein.
E. M: intercellular junction seal the bile canaliculi2. Portal area
It is found in the angles where adjancent hepatic lobules meet. Contain:
interlobular A and interlobular V:are surrounded by small amount of C. Tinterlobular bile duct: simple cubical epithelium
3. Hepatic blood circulationhepatic A→interlobular A→terminal pepate A→hepatic sinusoid→central V →sublobular V→hepatic V→portal V→interlobular V→terminal portal V
4. Passage of bilehepatocytes secrete bile→bile canaliculi→interlobular bile duct→left andright
hepatic ducts→common hepatic duct→common bile duct-→duodumum.
Practice ContentsL. M. specimen: pig liver, human liver, hepatic glucogen, kupffer cell, bile canaliculi,
the injection of hepatic vessels, glaabladder, pancreas, pancreas islet cells
(special staining).
E. M. graph: hepatocyte, hepatic sinusoid, bile canaliculi, perisinusoidal space and fat-
49
storing cell, pancreas cells and pancreas islet cells.
50
Chapter 10 Respiratory system
Learning Objectives1, know the structure of mucous membrane of nasal cavity and paranasal sinuses.
2, understand the structure of trachea.
3, understand the structure of lung and ultrastructure and function of alveoli.
Teaching ContentsGeneral description
1. Components
(1). Conducting portion -- nasal cavity, nasopharynx, larynx, trachea, bronchi,
bronchioles.
(2). Respiratory portion -- respiratory bronchioles, alveolar ducts and sacs,
alveoli.
2. Functions
(1). Inspiring warm, humidified, filtered oxygen and expiring carbon dioxide.
(2). Others: olfaction, voice, conversion of AT1 to AT2, synthesis of PGs, etc.
Trachea3 layers
1. Mucosa
(1). Pseudostratified ciliated columnar epithelium (respiratory epithelium)
a. Ciliated columnar cells -- sweep and remove inspired dust particles.
b. Goblet cells -- secrete mucus to adhere dusts.
c. Basal cells -- undifferentiated cells to produce other cells.
d. Brush cells and small granular cells.
(2). Lamina propria -- connective tissue with abundant elastic fibers, smooth
muscle bundles, lymphocytes and plasma cells (secrete SIgA to the surface).
2. Submucosa -- connective tissue with mixed glands secreting lysozyme and mucus.
3. Adventitia -- connective tissue with C-shaped hyaline cartilage rings supporting the
wall. The posterior gap is bridged by fibro-elastic membrane and smooth muscle.
Lungs1. General organization
(1). Main bronchi, after entering the lungs, branch repeatedly to form bronchial
51
tree, at end portion of which alveoli are connected.
(2). Divided into the conducting and respiratory portion.
1). Conducting portion -- intrapulmonary (lobar) bronchi, segmental bronchi,
bronchioles (<1mm), and terminal bronchioles (<0. 5mm). Passage of air.
2). Respiratory portion -- respiratory bronchioles, alveolar ducts, alveolar sacs,
and alveoli. Exchange of gases.
(3). Units of structure
1). Lobe: a lobar or secondary bronchus with all its branches and alveoli at
ends.
2). Lobule: a bronchiole together with its branches and connected alveoli;
pyramidal with the apex directed towards the lung hilus. Delicate connective
tissue separates adjacent lobules.
2. Morphologic changes of the conducting portion as the diameter decreases
(1). Epithelium
1). Pseudostratified ciliated columnar (thick→thin)→simple ciliated columnar.
2). Goblet cells -- more → few → absent.
3). Clara cells in small bronchioles secrete a thin secretion preventing mucus
plug.
(2). Glands -- more → few → absent.
(3). Cartilage plates -- more, large → few, small → absent.
(4). Smooth muscle -- scattered bundles → relatively more, thick → circular layer.
3. Respiratory portion
(1). Respiratory bronchioles
1). The wall is ruptured by scattered, thin walled outpocketings (alveoli).
2). The wall is lined with simple cuboidal epithelium.
3). Transitional area concerning with both gas conduction and gas exchange.
(2). Alveolar ducts
1). Elongate arrangements of many alveoli, which share a central, duct-like
space.
2). The wall between adjacent alveoli looks like knobs lined with simple
squamous epithelium.
3). Alveolar sacs:clusters of alveoli that have common spherical central space
into which alveoli open.
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4). Alveoli:terminal parts of respiratory system, thin-walled polygonal
compartments, site of gas exchange. Lined with two types of alveolar
epithelial cells (pneumocytes).
a. Type I cells (squamous cells)
①Thin squamou with sparse organelles.
②Covering most of the surface area of alveoli as a main component of
air-blood barrier.
b. Type II cells (secretory cells)
①Cuboidal or round cells interspersed between type I cells.
②Have more organelles especially lamellar bodies containing
phospholipids.
③Produce surfactant spreading over the alveolar surface. Surfactant
reduces surface tension and stabilizes alveolar diameter.
④Can divide and differentiate into type I cells in case of damage.
5). Interalveolar septum -- connective tissue between 2 adjacent alveoli. Mainly
contains:
a. extensive network of capillaries -- continuous capillaries come from
pulmonary artery and contain CO2.
b. rich elastic fibers -- provide with elasticity of the alveoli, distend in
inspiration and then cause expiration relying on their own elastic force.
c. alveolar macrophages -- present in interalveolar septum or alveolar lumen,
also called dust cells when phagocytosing dust particles.
6). Air-blood barrier -- structures across which gases must move between the
alveolar (O2) and the capillary (CO2) compartments, 0. 2-0. 5 mm thick. It is formed
by:
a. type I alveolar epithelial cells.
b. endothelial cells of a capillary.
c. basal laminae of type I cells and endothelial cells; the 2 basal laminae may
be fused, or with few connective tissue in between.
Practice ContentsL. M. Specimen: the mucous membrane of respiratory region and olfactory region,
trachea, lung, injection of pulmonary blood vessels.
E. M. graph: epithelium of trachea, alveoli and alveolar septum.
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Chapter 11 Urinary system
Learning Objectives1, understand the distribution, LM structure, ultrastructure and function of nephron,
collecting tubule and papillary duct.
2, understand the constitution, structure of juxtaglomerular complex and the function
of juxtaglomerular cell.
3, know the general structure of renal calyces, renal pelvis, ureter and bladder.
Teaching ContentsComponents and functions
1. Components -- the paired kidneys, paired ureters, urinary bladder and urethra.
2. Functions
(1). Produces and delivers the urine which contains final metabolic wastes.
(2). Regulates the balance of water, electrolytes, acid-base of the body, therefore
maintains homeostasis.
(3). Secretes hormone erythropoietin and other substances, such as renin, PGs.
Kidney1. General organization -- parenchymal organ divided into cortex and medulla.
(1). Enclosed within a thin capsule of dense connective tissue called fibrous
capsule.
(2). Cortex -- reddish, granular, the granules or dots are renal corpuscles.
(3). Medulla -- consists of 6-18 medullary or renal pyramids.
(4). Cortex and medulla are not totally separated from one another.
1). Cortical tissue projecting between pyramids is called the renal column.
2). Parallel bundles of tubules projecting into the cortex from the bases of each
pyramid are medullary rays. The cortical tissue between medullary rays is
cortical labyrinth.
(5). Structural unit
1). Lobe:one renal pyramid and the cortical tissue at its base and sides.
2). Lobule -- a single medullary ray and the cortical tissue surrounding it.
3). Uriniferous tubule -- epithelial-lined tubules consist of two portions,
nephrons and collecting tubules.
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4). Nephron -- consists of the renal corpuscle and renal tubule; classified into
cortical and juxtamedullary nephrons according to the location of its renal
corpuscle.
2. Nephron
(1). Renal corpuscle: found in cortex, has a vascular component, glomerulus
invested by a epithelial component, Bowman's capsule (glomerular capsule).
1). Glomerulus
①Network of fenestrated capillaries resting on a thick basement membrane.
②Capillaries are fed by an afferent arteriole and drained by an efferent
arteriole.
③Between capillaries lies mesangium containing mesangial cells.
2). Bowman's capsule -- double-layer cup of epithelium
①Outer or parietal layer is squamous epithelium.
②Inner or visceral layer covers the capillaries and is formed by podocytes,
which have large primary processes and many secondary processes. The
secondary processes interdigitate and wrap around the capillaries.
③Basement membrane of podocytes fuses with basal lamina of capillaries.
④Narrow slit pores are present between adjacent secondary processes and
bridged by slit membrane.
⑤The space between parietal and visceral layers is called Bowman's space.
3). Vascular pole and urinary pole of renal corpuscle
①The end at which the afferent and efferent arterioles enter and leave.
②The urinary pole is the end opposite the vascular pole at which parietal
layer of Bowman's capsule is continuous with that of the proximal
convoluted tubule.
4). Function -- producing filtrate through Filtration barrier between blood in
glomerular capillaries and urinary space, which has 3 layers: fenestrated
endothelium, glomerular basement membrane, and slit membrane of
podocytes.
(2). Renal tubule -- divided into 3 segments: proximal tubule (convoluted and
straight segments), thin segment, and distal tubule (straight and convoluted
segment).
1). Proximal convoluted tubule -- located in the cortex around its parent renal
55
corpuscle.
①Longest and thickest segment with relatively small lumen.
②Lined with single layer of acidophilic cuboidal cells.
③Free surface of cells has well-developed brush border (micrivilli).
④Lateral margin is not distinct (because of interlocked lateral
processes).
⑤Basal longitudinal striations (plasma membrane infoldings and
mitochondria).
⑥Main reabsorption site: all nutrients, most of water and ions such as Na+.
2). Thin segment and the loop of Henle -- located in the medulla and
medullary ray.
①Thin segment is thin and lined with squamous epithelium.
②The loop of Henle is an U-shaped tubule consisting of straight portions of
proximal and distal tubules and thin segment in between.
③Function of the loop of Henle is to generate a hypertonic urine.
3). Distal convoluted tubule -- also located around its parent renal corpuscle.
①Thinner than proximal convoluted tubule, with relatively large lumen.
②Lined by simple cuboidal epithelium and cells are light stained with no
brush border.
③Intercellular borders are not seen.
④Abundant basal infoldings and mitochondria.
⑤Reabsorption of Na+ and excretion of K+ under the influence of
aldosterone; Reabsorption of water under the influence of antidiuretic
hormone (ADH).
(3). Collecting tubule -- mainly located in medullary ray and medulla.
1). Lined by cuboidal or columnar (papillary duct) cells with pale stained
cytoplasm.
2). Having distinct intercellular boundaries.
3). Functions as distal convoluted tubule adjusted by the same hormones.
(4). Juxtaglomerular apparatus -- located at the vascular pole, consists of 3
structures, involved in the regulation of systemic blood pressure.
1). Juxtaglomerular cells
a. Modified smooth muscle cells in the wall of afferent arterioles.
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b. Contain secretory granules of renin
2). Macula densa
a. A specialized region of the distal tubule adjacent to the vascular pole.
Cells are tall and closely packed.
b. Thought to be chemoreceptor perceiving the change of [Na+] in distal
tubule lumen and regulate renin secretion.
3). Extraglomerular mesangial cells.
Excretory passages1. Include minor and major calyces, renal pelvis, ureters, urinary bladder and urethra.
2. The wall shows 3 layers: mucosa, muscularis and serosa or adventitia. The mucosa
is lined with transitional epithelium except the final segments of the urethra.
Practice ContentsL. M. Specimen: kidney, juxtaglomerular cell, macular densa, injection of renal blood
vessels, ureter and bladder.
E. M. graph: renal corpuscle, capillary of glomerulus, podocyte, filtration barrier,
mesangial cell, proximal tubule, distal tubule.
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Chapter 12 Skin(individual study)
Learning objectives:1. Understand the basic structure of skin,know the keratinizing processes of
epidermis.
2. Know the distribution,structure and function of melanocyte and Langerhan’s cells.
3. Know the structure and function of sebaceous gland and sweat gland.
4. Know basic structure and growth of hair.
individual study contents:1. skin:the basic structure of epidermis and dermis;the
layers,microstructure,ultrastructure and keratinizing processes of epidermis;the
distribution,microstructure,ultrastructure and function of melanocyte,Langerhan’s
cell and Merkel cell;the layers of dermis;the structure of papillary layer and
reticular layer.
2. the appendixes of skin:the structure,ultrastructure and function of sweat gland;the
structure and function of myoepithelial cell;the distribution and structure of large
sweat gland;the structure and function of sebaceous gland;the composition of
hair;the structure of hair shaft,hair root,hair follicle,hair bulb,hair papilla;the
growth and replace of hair;the position,structure and function of arrector pili
muscle.
3. regeneration of skin:the phusiological regeneration and compensative
regeneration of skin.
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Chapter 13 Sense Organ
Learning Objectives1, understand the structure and function of the wall of eye ball and lens system.
2, know the structure of eyelid.
3, know the structure of membranous labyrinth of inner ear, understand the structure
and function of crista ampullaris, maculae staticae and spiral apparatus.
individual study ContentsEye
1, eye ball: fibrous tunic, vascular tunic and retina, the lens system.
Fibrous tunic: the structure and physiological feature of every layer of cornea.
The structure of sclera.
Vascular tunic: the structure of choroids membrane. The structure of ciliary body,
the distribution and function of ciliary muscle. The ultrastructure of cilary
epithelium and its relationship with the formation of aqueous humor, the
composition and significance of blood-aqueous barrier. The structure of iris, the
structure and function of dilator muscle of pupil and constrictor muscle of pupil.
The structure of sinus venosus sclerae , trabecular web and their role in the
circulation of aqueous humor.
Retina: the LM structure, ultrastructure and function of pigment epithelium, rod
cell and cone cell. The structure and function of bipolar cell, ganglion cell,
horizontal cell and amacrine cell. The structure and function of Miller cell. The
layers of retina. The structure and function of macula lutea, papilla of optic nerve
and optic nerve.
The lens system: the eye chambers and aqueour humor, the circulatory path of
aqueous humor. The structure and function of lens and zonular ciliaris. The
structure of vitreous body.
2, eyelid: the structure of eyelid, zeisian gland, Moll’s gland and Meibomian gland.
Ear
1, external ear: the structure of auricle and the wall of external auditory meatus.
2, Middle ear: the structure of tympanum and mucous membrane of auditory tube, the
LM structure of tympanic membrane.
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3, internal ear: the structure of the wall of osseous labyrinth, the structure of
membranous labyrinth. The position, structure and function of macula sacculi, macula
utriculi and crista ampullaris. The structure of every part of cochlea wall, the structure
and function of spiral apparatus. The formation and absorption of inner lymph and
outer lymph.
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Chapter 14 Endocrine System
Learning objectives:1. Know the general structure of endocrine gland and ultrastructure of endocrine
cells which secrete the amino acid derivative hormone,peptide hormone and
steroid hormone.
2. Understand the microstructure and its hormone of thyroid,parathyroid and adrenal
gland.
3. Understand the microstructure and its hormone of pituitary,and relationship
between hypothalamus and pituitary.
Teaching contents:Introduction
1. Consists of individual endocrine glands, and diffuse endocrine cells that are present
in other organs. Together with the nervous system, it regulates different functions
of the body.
2. Endocrine glands:thyroid, parathyroids, adrenals, pituitary and pineal glands
1). Endocrine glands are ductless.
2). Cells arranged in glomerulus, cords, reticulum or in follicles.
3). Rich in blood and lymphatic capillaries between cells.
4). Release hormones either into the vascular system (endocrine), or to their
surroundings (paracrine), and bind to specific receptors of target cells.
3. Endocrine cells: 2 types according to chemical nature of hormones released
1). Nitrogen-containing hormone-secreting cells
a. Found in thyroid, parathyroids, adrenal medulla, pituitary and pineal
glands, etc.
b. Contain RER, Golgi complex and membrane bound secretory granules.
c. Hormones are secreted by exocytosis.
2). Steroid hormone-secreting cells
a. Found only in adrenal cortex and ganads.
b. Contain abundant SER, mitochondria with tubular cristae and lipid
droplets.
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c. Hormones are secreted by diffusion.
Thyroid – largest endocrine gland1. General structure
(1). Thin capsule of loose connective tissue sends septa into parenchyma,
dividing the gland into lobules.
(2). Each lobule consists of follicles, which are functional units and varied in size.
(3). Between follicles is a delicate connective tissue rich in fenestrated capillaries.
(4). The thyroid also contains parafollicular cells.
2. Thyroid follicles
(1). Composed of a simple epithelial sphere whose lumen contains colloid.
(2). Follicular epithelial cells
1). Height of cells ranges from squamous to columnar, depending on the
functional activity of follicles.
2). The cytoplasm is weakly basophilic or acidophilic.
3). Ultrastructure:
①Apical surface is covered by numerous microvilli.
②Cytoplasm rich in RER in basal part, well-developed Golgi complex in
supranuclear area, secretory granules and pinocytotic colloid vesicles in
apical part and abundant lysosomes.
③Cells are joined laterally by junctional complexes, preventing thyroglobulin
leakage from follicles into surrounding stroma.
(3). Colloid
1). Homogeneous, acidophlic, gelatinous substance.
2). Chemical composition is iodinated thyroglobulin.
3). Vacuoles at the periphery may represent pinocytosis of colloid.
(4). Function: synthesis and release of thyroid hormones (T3, T4)
1). The process involves:
①Synthesis of thyroglobulin (TG) in RER and Golgi apparatus. TG is
transported in secretory granules and released into lumen of follicles.
②Iodination of TG. Follicular cells take up circulating iodide, which is
activated via oxidation by peroxidase and combines at the microvillus-
colloid interface with tyrosine residues of TG.
③Storage. The iodinated TG is stored as colloid in the follicular cavity.
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④Pinocytosis. When stimulated by thyrotropin, follicular cells take up
iodinated TG from the cavity, forming pinocytotic vesicles.
⑤Liberation of T3 & T4. Pinocytotic vesicles then fuse with lysosomes and
iodinated TG is degraded by proteases into free thyroxine (T4) and
triiodothyronine (T3), which are released into fenestrated capillaries.
2). T3 and T4 increase rate of metabolism and influence development of central
nervous system during fetal and neonatal life.
3. Parafollicular cells or C cells
(1). Located between follicular epithelial cells or between follicles as isolated
clusters.
(2). Large and pale stained with H & E, argyrophilic granules with silver staining.
(3). Under EM, many small secretory granules.
(4). Secrete calcitonin, which lowers blood calcium level by inhibiting bone
resorption of osteoclasts and osteocytes.
Adrenal glands1. General description
(1). Covered by a capsule of dense connective tissue, which, with abundant
sinusoids, extends into the interior of glands.
(2). Parenchyma consists of an outer adrenal cortex derived from mesoderm, and
an inner adrenal medulla from the neural crest.
(3). The cortical cells are steroid-secreting, and the medullar cells are nitrogen
hormone- secreting.
2. Adrenal cortex -- subdivided into three layers according to cell arrangement
(1). Zona glomerulosa
1). Beneath the capsule, occupy 15% of total volume of the glands.
2). Composed of round clusters of columnar cells surrounded by capillaries.
3). Secrete mineralocorticoids, primarily aldosterone, which maintain
electrolyte and water balance by acting on distai renal tubules and stimulating
resorption of sodium.
(2). Zona fasciculata
1). Most thick layer in middle account for 65% of total volume of glands.
2). Composed of straight cords of large, polyhedral cells with acidophilic,
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sponge cytoplasm.
3). Cells have typical ultrastructural characteristics of steroid-secreting cells.
4). Synthesize glucocorticoids: mainly cortisol and corticosterone, which
regulate carbohydrate, protein and lipid metabolism, and also suppress
immune responses.
(3). Zona reticularis
1). Innermost layer of smaller cells arranged in anastomosing cords, 7% of total
volume.
2). Produce sex hormones, mainly androgens, and small amounts of cortisol.
3. Adrenal medulla
1). Composed of polyhedral cells arranged in nests or short cords.
2) Cells contain chromaffin granules, so called chromaffin cells.
3). Synthesize and release epinephrine and norepinephrine by 2 different
groups of cells.
4). Epinephrine increases the heart rate. Norepinephrine increases the blood
pressure and blood flow to the heart, brain and skeletal muscle.
Pituitary Gland (hypophysis)master gland regulating other endocrine glands
1. Introduction
1). Consists of two parts: adenohypophysis develops from oral ectoderm, and
neurohypophysis from neuroectoderm.
2). The adenohypophysis includes 3 parts: pars distalis or anterior lobe, pars
intermedia, and pars tuberalis.
3). The neurohypophysis includes 3 parts: pars nervosa or posterior lobe,
infundibular stalk and median eminence. Pars nervosa and pars intermedia
make up posterior lobe.
2. Pars distalis – largest part containing 3 types of cells interspersed with sinusoids
(1). Acidophil cells – 40%
1). Round or ovoid, exhibiting acidophilic, and numerous coarse secretory
granules under EM. 2 types of acidophil cells.
2). Somatotrophs synthesize and release growth hormone, which stimulates
body growth, particularly growth of long bones.
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3). Mammotrophs secrete prolactin, which initiates and maintains the milk
secretion after pregnancy.
(2). Basophil cells – 10%
1). Slightly larger than acidophil cells, with basophilic cytoplasm. 3 types with
EM and immunohistochemical techniques.
2). Thyrotrophs secrete thyrotropin or thyroid stimulating hormone (TSH),
which stimulates growth of thyroid follicles and synthesis and release of
thyroid hormones.
3). Corticotrophs secrete adrenocorticotrophic hormone (ACTH), which
stimulates secretion of glucocorticoids from zonae fasciculata and reticularis
of adrenal cortex.
4). Gonadotrophs secrete follicle-stimulating hormone (FSH) and luteinizing
hormone (LH). FSH promotes ovarian follicle development in females and
spermatogenesis in males. LH promotes ovulation and development of the
corpus luteum in women and, Leyding cell stimulation and androgen
secretion in men.
(3). Chromophobe cells – 50%
1). Clusters of small cells without distinct boundaries, and pale stained.
2). Few secretory granules, indicating they are undifferentiated precursor cells
or degranulated chromophils.
3. Pars intermedia
(1). Composed of chromophobes and basophil cells arranged either in cords or in
colloid-containing follicles.
(2). Secretes melanocyte stimulating hormone (MSH) in fish and amphibia.
4. Pars tuberalis
1). Surrounds the infundibulum, and cells arranged in cords separated by
sinusoids.
2). Most cells secrete FSH and LH in humans.
5. Relationship between pars distalis and hypothalamus
(1). Activities of the cells in the pas distalis are controlled by hypothalamic
neuroendocrine neurons that produce peptide releasing hormones and
inhibitory hormones, which are transported to the pars distalis through the
hypophyseal portal system.
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(2). Hypophyseal portal system includes
1). Primary capillary plexus in the stalk and median eminence, formed by
superior hypophyseal arteries.
2). Hypophyseal portal veins joined in pas tuberalis from primary plexus.
3). Secondary capillary plexus in pas distalis, formed from portal veins.
5. Neurohypophysis
(1). Contains large numbers of unmyelinated nerve fibers, sinusoids, pituicytes.
(2). Unmyelinated nerve fibers contain neurosecretory granules, which often
accumulate in dilated portions, Herring bodies, of the axons. They originate
from neurons of hypothalamic supraoptic and paraventricular nuclei.
(3). Pituicytes are glial cells with irregular shape and short processes contain lipid
droplets and pigment granules in their cytoplasm.
(4). Function: stores and releases vasopressin (antidiuretic hormone, ADH) and
oxytocin.
1). Vasopressin stimulates water resorption in kidneys and contraction of
vascular smooth muscle.
2). Oxytocin promotes contraction of uterine smooth muscle during parturition
and contraction of myoepithelial cells in mammry glands during lactation.
Practice contents:L. M. specimen:thyroid,parathyroid,adrenal gland,pituitary.
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Chapter 15 Male Reproductive System
Learning Objectives1, know the general structure of testis. Understand the structure of seminiferous
tubules, the processes of spermatogenesis, blood-testis barrier, the structure,
ultra-structure and function of interstitial endocrinal cells.
2, know the structure of epididymis and ductus deferens.
3, understand the structure of prostate.
Teaching ContentsTestis
1. general structure
(1)envelope:
serous membrane: vesceral tunica vaginalis
tunica albuginea: dense CT
parenchyma: lobule --seminiferous tubules and straight tubules (1-4 pieces)
interstinum: loose CT
mediastinum testis: dense CT, ※rete testis is located at
2. seminiferous tubules
(1). constitute:
1). limiting membrane:collagen fiber,myoid cell (3-5 layers),and basement
membrane.
2). spermatogenic epithelium: 2 sorts of cells
a. spermatogenic cell:
①spermatogonium:close to the basement membrane,D=12um,round nuclear
②primary spermatocyte:(stop in the prophase of first meiosis for 22
days ),D=18um,nuclear as woollen ball (first meiosis)
③secondary spermatocyte: D=12um,not easy to be seen for short-lived and
quickly divide into second meiosis.
④spermtide: D=8um,small in shape,close to the lumen,dark nuclear
⑤spermatozoon:L=60um (head=5um,tail=55um),tadpole in shape→
spermiogenesis (to shape in form):
Nu→elongate and partial to one side
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Gol→ crosome (special lysosome)
Centriole--proximal→keeped
distal→axoneme (main part of flagellum)
Mit →sheath
other cytoplasm→are expeled from cytoplasm.
It is about 64 days from spermatogonium to spermatozoon.
b. Sertoli' cell (supporting cell)
Shape:
LM: pyramidal in shape ,irregular Nu and clear nucleolus
EM: abundant SER, Gol, Mit, Lysosome
upper--close to the lumen
middle--project to lateral processes
low--close to the basement membrane
There is tight junction between the lateral processes, and spermatogenic
epithelium is divided into basal and abluminal compartment.
Function: support, protect, nourish, regulate and release inhibin (control
FSH) and androgen binding protein
c. blood-testis barrier:
Constitute: endothelium and basement membrane of capillary limiting
membrane (including CT,myoid cell and basement . membrane of
seminiferous epithelium) tight junction between the sertoli' cells
Function: provide micro-environment for spermatogenesis avoid spermatozoon
passing through the wall of seminiferous tubule and from
individualimmune reaction
3. interstinum
(1). constitute:
loose C. T among the seminiferous tubules
besides blood cap and lymphatics, there are interstitial cells (Leydig cell)
Leydig cell:
LM:D=15-20um,round Nu and clear nucleolus,acidophilia of cytoplasm
EM:feature of steroid-secreting cell
(2). function: secrete testosterone
maintenance of male secondary sex characteristics
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help to development of genital duct and accessory gland
help to development of spermatozoon
4. straight tubules ( tubulus rectus )
(1)position: near the mediastinum testis
(2)shape : straight and short canal
(3)structure: simple cuboidal cells without seminiferous epithelium(thinner wall)
5. rete testis
(1)position: within the mediastinum testis
(2)shape : labyrinthine network (large and irregular lumen)
(3)structure: as straight tubules
Practice ContentsLM specimen: testis, epididymis, prostate, ductus deferens, spermatozoon smear.
E. M. graphy: sertoli cell, interstitial cell, spermatozoon.
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Chapter 16 Female reproductive systemLearning Objectives1, understand the structure of ovary, the growth and development of ovarian follicle.
The conception of ovulation; the formation, structure and function of corpus
luteum; know the relationship between ovary and pituitary hormone.
2, understand the structure of uterus, the relationship between the cyclic changes of
endometrium and ovary.
3, know the structure of oviduct, vagina and mammary gland.
Teaching ContentsOvary
1. consist of covering:
(1)surface (genital) epithelium--simple cuboidal epithelium (mesothelium)
(2)tunica albuginea--dense CT
(3)parenchyma:
1). cortex: a lot of follicles in various stage in development and regression with
C. T. among the them.
2). medulla: loose CT
(3) the hilus: near the ovary mensentory, the region where vessels and nerves
enter and leave ovary.
the hilus cell:
LM:the structure as interstitial cell of testis
EM:steroid secreting cell
Function:secrete androgen
2. follicle development
follicle: the cell group which consists of one large oocyte and many small follicular
cells
(1) primordial follicle
position: peripheral portion of cortex
shape:small
quantity: large in number
consist of
1). primary oocyte d=40um (prophage of first meiosis) from oogonia
LM: eosinophilic cytoplasm,large vesicular nucleus with prominent nucleolus.
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EM: SER surround nuleus in circular lamina
2). follicular cell:
LM:single layer of squamous cell
EM:there is gap junction between oocyte and follicular cell
(2) primary follicle:
position- deep portion of cortex
consist of:
1)primary oocyte : d=50- 80um
EM:cortical granule (ly);
2)zona pellucide appear surrounding oocyte,containing zona protein,
including ZP1, ZP2, ZP3(receptor to spermatazoon)
LM:homogeneous acidophilic membrane
EM:process from oocyte and follicular cell connect each other
and form gap junction
3)follicular cell: 5--6 layers
4)basement membrane is obvious
(3) secondary follicle
position: deep of cortex
consist of:
1)primary oocyte: larger d=125--150um
2)follicular cell: 6--12 layers
3)corona radiata: a layer of columnar cell surrounding the zona pellucide
4)stratum granulosum:the other layers of cuboidal cell
5)follicular antrum appear
6)cumulus oophorus:the prominence containing oocyte and project to the
follicular antrum
7)follicular fluid: nourishment from capillary of follicular membrane steroid
horemone from follicular cell
8)basement membrane is obvious.
9)follicular membrane : (theca folliculi)
theca interna--rich in capillary and theca cell
theca externa--rich in fiber and some SM
theca cell:
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LM:similar to fibroblast, Nu in the center; cytoplasm as spumescence
EM:same as steroid secreting cell
(4) mature follicle
position: close and project to the surface of ovary
volumn: the largest d=2cm
The primary oocyte finish the first meiosis and form the second oocyte and a
polar body (little cytoplasm) before the 36-48h of ovulation, then begin to
secondary meiosis and stop the metaphage of secondary meiosis.
(5) ovulation
concept: It is a process which mature follicle rupture and secondary oocyte is
expelled from ovary.
process: follicular fluid--internal pressure of follicular antrum--bulging of ovary--
surface thiner and weaker area--follicular stigma (short of blood and
pellucide) -- ezymes from follicular fluid break up-- follicular wall
rupture-- pulsion of secondary oocyte, zona pellucida and corona
radiata from ovary
If fertilization within the 24h--finish the secondary meiosis--mature
oocyte and secondary polar body. Or , retrogress and disappear
3. corpus luteum:
(1)concept: After ovulation, the ruptured follicle colla[ses. then cap and CT
fromtheca invade into granulosa cells. At last, the cell group with
temporary endocrine function is formed, under stimulated by LH.
(2) type of lutein cell:
Cell cytoplasm
position amount body staining secreting
granulosa central part large large pale relaxin
cell progesterone
theca peripheral small small dark androgen
cell estrogen
3)development:
After fertilization,corpus luteum of pregnancy--after 5-6m, corpus alblians.
If no fertilization,corpus luteum of menstruation--after 12-14d, corpus alblicans.
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4. atresic follicle:
(1)concept: follicle which stop growth-process and degenerate at any stage of
follicular development
(2)feature: large in number
various in shape, Nu--dissolvedzona pellucida--twistedcorona radiata-be free
granular cell-- relax
WBC--invaded
5. interstitial gland: poorly developed in humans, secrete androgen→estrogen
Oviductconstitute:
1. mucosa: a lot of folds which are longitudinally-oriented.
(1). epithelium:a layer of columnar cell which change according to menstrual
cycle
1). ciliated cell: with cilium (at the infundibulum and ampulla)
2). secretory cell-- with Mv , secreting mucous
2. lamina propria: thiner CT and little SM
3. muscularis: inner circular S. M , outer longitudinal SM
4. serosa: mesothelium and subserous loose CT
Uterus1. structure of the wall:
(1) perimetrium: mostly serosa , partly fibrous membrane
(2) myometrium:
1). SM--sharp to horemone:
estrogen: Mf increase in quantity (tumor)
progesterone: Mf increase in volume ( L=50-500um)
relaxin: Mf relax
oxytocin: Mf contract
2). CT: with undifferentiated mesenchyma cell--as fibroblast
LM: flatted Nu , basophilic cytoplasm
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EM: protein-secreting cell
(3) endometrium:
1)by function:
a. functional layer: thicker (4/5 of endometrium), implanted position
beocme decidua in pregnancy
slough in menstrual cycle
b. basal layer: thin (1/5 of endometrium), repair functional layer
not slough in menstrual cycle
2). by structure:
a. simple columnar epithelium
ciliated cell: little in numbe, round Nu and close to the free side,pale in
staining.
secretory cell: larger in number, oval Nu and close to the basement side, dark
in staining, rich in Mv under EM.
b. lamina propria: loose CT
sroma cell: irregular cell-shape, lower in differentiation
uterine gland:the epithelium, which maimly consists of secretory cells,
invaginate into lamina propria and forms many tubular gland.
2. menstrual cycle (28d)
(1) concept: It is the cylic histological change of endometrium of non-pregnant female
during the period from sexually mature (puberty) to menopause.
(2) 3 phases
phase menstrual proliferation secretory
date 1st-4th day 5-14th day 15-28th day
ovary Luteum follicle ovulation
→albicans develop corpus,luteum
hormone estrogen↓ estrogen↑ estrogen↑
progesterone↓ progesterone↑
endometrium Bleeding and Thicker (1→3mm) Thicker(3-5mm),secreting
slough Coiled Stroma cell proliferate Stroma cell→enlarge
A spasm→ Uterine gland extend →predecidual cell
functional layer to the deep of lamina →Not enlarge
bloodless and propria →granular cell
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putrescence Coiled A begin to Uterine G elongate and
→slough extend and curve enlarge in cavity which
is full of matter, Coiled
A reach to the superficial
portion of endometrium
Practice ContentsL. M. specimen: ovary, oviduct, uterus
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Chapter 17 General Embryology (early development)
Learning objectives:1. Know the definition of embryology and the development periods of the fetus .
2. Know significance of capacitation of spermatozoon.
3. Understand the definition, place, time ， process, conditions and the
significances of fertilization.
4. Know the meaning of the cleavage, morula and the blastocyst.
5. Understand the structure of blastocyst.
6. Understand the definition, time, place, process, and conditions of implantation,
and the ectopic implantations.
7. Understand the meaning of the decidua and the deciduas reaction .
8. Understand the formation and the differentiation of trilaminar germ disc.
9. Understand the composition ,structure and significance of fetal membrane ,.
10. Understand the structure and the function of the placenta.
11. Know the calculation of the expected delivery date and the measuring method of
fetal age.
Teaching Contents:Fertilization
1. concept: process which sperm fuses with ovum and form a spermatovum(zygot).
2. essential conditon:
(1)mature gamete
1)ovum stop in metaphase of secondary meiosis.
2)sperm finished the secondary meiosis and get ability of movement (stay in
epididymis for 2 weeks)
(2)capacitation: get ability of combination with ovum cancel decapacitation factor:
glycoprotein on the sperm the sperm stay in the female genital tract for 5--6h. If
not pregnancy ---(wash sperm with special fluid)
(3)quantity of sperm 3--5 hundred million
(4)gamete come to meet each other:
1)time: in 24h after ovulation
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2)space: unobstructed in genital tract
3. process
at first, sperm combine with ZP3→releasing enzyme from acrosome (acrosome
reaction) →penetrate through the corona radiate→penetrate through the zona
pellucida→membrane fusion→sperm nuclear enter→male pronucleus→ovum finish
II meiosis →female pronucleus→nuclear membrane disappear →mixed by
chromosome →zygot
4. zona reaction: preventing from polyspermy
When sperm nuclear entering, oocyte releases granule →decrease the transitivity
of the zona, so as to prevent other sperm to penetrate.
5. significance
(1). return to the quantity of chromosome ( 23 pairs in human being ) for
stabilization of spices
(2). produce different hereditary feature to parents within the certain range
(3). determine the sex of fetus
(4). arous the cleavage which is the beginning of the new individual
6. artificial fertilization:
fertilization in vitro (FIV) →embryo transfer(ET) → Test tube baby
Early stage of human embryogeny1. cleavage and . blastulation (first week)
(1). cleavage
1)concept: spermatovum begin to mitotic division
2)feature :split rapidly →blastomere (similar shape of cell), volume of cell is less
and less(zona pellucida exit still)
3)process: 2(30h) →4(40h) →12-16(72h) →morula
oviduc → uterus
(2). blastulation: blastocyst forming
1)feature: cavity in central portion of morula occur
cells arrange in order (inner cell mass, trophoblast)
zona pellucida disappear and get rid of the limit to volume
2)process: fluid from uterine cavity¡ →morula →some space¡ →blastocele
2. implantation (second week)
(1)concept process which blastocyst implant in the endometrium. (imbed)
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(2)process: (6th--12th day) Enzyme from polar trophoblast (close to inner cell
mass) solve the uterine mucosa, and blastocyst take the place, then,
is covered by adjacent endometrium
(3)essential condition:
secretory phase in endometrium controlled by hormone
normal internal enviroment in uterus
blastocyst reach the position and zona pellucida disappear
(4)position:
normal: ante/post wall of uterine body, uterine bottom
abnormal: ectopic pregnancy (especially in oviduct)
placenta previa (close to the uterine neck)
dystocia (difficult labour )
(5)impact:
1)decidua formed: functional layer of endometrium is named , after implantation.
a. division:
decidua basilis: deep to blastocyst
decidua capsularis: surface to blastocyst
decidua parietalis: the other decidua
b. decidua reaction: stimulation from implantation---some changes take
place in the endometrium. (blood vessels dilate, gland secrete,
cytoplasm in decidual cell containing nurishment)
2)trophoblast changes:
proliferate:increase in layer of cell
surface layer: syntiotrophoblast (boundary between cells disappear)
deep layer: cytotrophoblast (proliferating rapidly)
3. formation of embryonic layer
(1)two embryonic layer (2nd week)
1)process: cell close to blastocele in inner cell mass →2 layers of cell :
a layer which consists of cuboidal cells is called as hypoblast.
the other which consists of columnar cells is called as epiblast.
2)embryonic disc:
constitute :composed of epiblast, hypoblast and basement membrane
shape: disc-shaped (oval disc)
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action: primordium of new individual ( human body)
3)relating structure
①formation of yolk sac
a. at beginning of 2nd week, internal surface of the cytotrophoblast --a layer
of squamous cell →primary yolk sac
b. at the end of 2nd week, periphery of hypoblast---a layer of cuboidal cell
connecting the bundary of hypoblast---extend along the primary yolk sac
→scondary yolk sca (replace the primary)
②formation of amniotic cavity
There is space between the aminiotic cell and epiblast cytotrophoblast of polar
trophoblast ---a layer of squamous cell---amniotic cell ---line to boundary of
epiblast
The wall is composed of amniotic cell and epibast
③formation of exoembryonic mesoderm
a. at beginning of 2nd week, the loose T (mesenchymal tissue) appears
among amnion, yolk sac and trophoblast.
b. at end of 2nd week, small space appear in exoembryonic mesoderm
--fused gradually--forming large cavity(exocoelom) :
parietal layer:lines internal sureface of trophoblast, and on the external
surface of amnion
visceral layer: on the external surface of yolk sac
Chorion: trophoblast cell and adjacent exoembryonic somatopleuric
mesoderm.
Amnion: amniotic cell and adjacent exoembryonic somatoplueric mesoderm.
④formation of body stalk
Exoembryonic mesoderm between polar trophoblast and amnion migrates
from the dorsal to the ventral of embryo and forms a cord-shaped
(2)three embryonic layer (3rd week)
1)process: at the beigining of 3rd week:
2)primitive streak: cells of epiblast at caudal portion proliferate in the
intermediate line of embryonic disc and project to the amniotic cavity.
3)primitive groove: proliferating and migrating into the deep of the primitive
streak intraembryoic mesoderm: cells at bottom of the groove proliferate
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and migrate to both sides and cephalic and caudal direction.
4)division: somitic mesoderm intermediate mesoderm lateral mesoderm
5)areas without mesoderm: oropharyngeal membrane --in front of notochord
cloacal membrane -- behind primtive streak
6)ectoderm: the epiblast above the mesoderm, after mesoderm appear
7)endoderm: a layer of cells from epiblast whose enter and proliferate in
hypoblast.
8)relating structure
①notochord
a. primitive knot : cells of cephalic portion of the streak proliferate and form a
node-like.
b. primitive pit : at the center of knot (invaginated), cell of bottom in the pit
proliferate and migrate towards the cephalic between endoderm and
ectoderm
c. notochord: degeneracy into the intervertebral disc
②neural canal :
ectoderm, which is adjacent to the notochord, is induced to proliferate by
notochord →neural plate →neural groove:(18 days) → neural fold: longitudinal
prominence beside the groove →neural canal: (the end of 3rd week)
anencephaly
③allantois :
a blind sac proliferated from the caudal of the root of yolk sac to the body stalk.
④chorion formation
4. major differentiation of embryonic layer (4th-8th week, organo genetic period)
(1)ectoderm---neural canal→brain ,spinal cord
---neural crest(at superolateral to the neural canal)→neural ganglion,
medulla of suprarenal gland.
---epidermis and appendages (hair ,sweat gland,sebaceous gland)
lens, adenohypophysis, mem labyrinth, epithelium of cornea and
oral and nasal cavity,
(2)mesoderm:
It differentiates all of structures, except for the ones coming from the ectoderm
and endoderm.
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paraxial mesoderm:spinal column,muscle dermis beside notocord, symmetry
intermediate mesoderm:primordium of urinary and genital system
lateral mesoderm:parietal mesoderm:skeletal M of the trunk and limbs, serosa
(parietal layer),visceral mesoderm, serosa (visceral layer),smooth M, CT
mesenchyma :loose tissue with mesenchymal cells, ground substance
(matrix),possess the ability of potential differentiation (M,CT, cardiovascular system)
(3)endoderm→primitive gut:
→primordium of digestive and respiratory system
→thyroid and parathyroid gland, thymus
5. formation of embryonic body (5-8th week)
(1)shape :
as newborn ,there is different proportion in shape (larger head )
be seen the head and facial feature; the neck and limbs(fingers)
external reproductive organ (not distinct sex clearly )
(2)viscera:basically take shape
(3)sensitive stage of organ-malformation:easy to cause malformation with
medicine, virus ray and so on
6. auxiliary structure
concept: a temporary structure which does not belong to the fetus itself but can
nourish and protect fetus.
(1)Fetal membrane
1). consists of:
①chorion:3rd —8th week
constitution: the parietal layer of extraembryoic mesoderm and trophobla st.
division:chorionic plate--bottom of chorion
villous:prominent into decidua
primary villus:made of trophoblast
second villus:add to extraembryonic mesoderm
tertiary villus:add to the blood capillary
development: after 8th week,
chorion near the basilis deciduas:villous chorion (frondosum)
chorion near the capsularis deciduas:smooth chorion (laeve)
hydatidiform mole:chorion oedema
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②amniotic membrane: 2nd —40th week
constitution: made of the amniotic epithelium and extraembryonic
somatopleuric mesoderm.
development: end of 2nd week, amniotic cavity enlarge-- amnion close to
chorion – ectocoeloma disappear --make the yolk sac ,allantois ,
body stalk into umbilical cord
action : secreting amniotic fluid (1500-1000ml)
protecting(shake, adhesion)
wash the delivery path
enlarge the neck of uterus
examination in cellology (sex,chromosome)
③yolk sac: 2nd —6th week
constitution: primary yolk sac from cytotrophoblast
secondary yolk sac: from endoderm
development: formed in 2nd week
the proximal portion---primitive gut;
the distal portion--- degeneracy--merged into umbilical cord in 6th week
action : induce extraembryonic mesoderm near the yolk sac----blood
island(3rd week) ---replaced by liver (5th week)
endoderm near the allantois ---primordium of genital gland
④allantois : 3rd —6th week
constitution: from endoderm of caudal portion of yolk sac
development: the root --roof of urinary bladder , urachus
the others--retrograde (blood vessels remain and changes into
umbilical A,V)
action: not developed in human being
⑤body stalk: 2nd –6th week
constitution: extraembryonic mesoderm between the embryo and
cytotrophoblast .
development: merged into umbilical cord in 6th week
action: only path between the embryo and chorion in early stage of
embryogenesis
⑥umbilical cord: 6th w----
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constitution: a sort of mucoid tissue which contains yolk stalk, allantois A
and V, body stalk
D=1-2cm, L=55cm;
longer-- surrounding the fetal neck;
shorter--placenta early separated from uterus
development: amniotic cavity enlarge --body stalk enlong --
extraembryonic coelom reduce --surrounding some structures(wrap
up) --formed in 6th week
action: only path between the embryo and chorion in later stage of
embryogenesis.
(2)placenta
1). concept:
shape:a disk-shaped organ which consists of villous chrion and basilis
deciduas.
Function:an important organ which exchanges material between the fetus and
mother
Position:the thick area of the sac which is constituted by amniotic membrane
chorion and decidua,
2). division:
fetal portion:amniotic membrane(smooth),frondosum (chorionic plate and
villus)
mother portion:basilis decidua (basilis plate and placental septum),rough with
cytoledon
3). blood vessels:
blood from mother : uterine A --space among the villus ---uterine V
blood from fetus : umbilical A---capillary in villus ---umbilical V
4)placenta barrier: formed after 3rd month in embryogenesis
constituted:
12-15th week:( 6 layers) trophoblast ,basement membrane CT in villus,
basement mem,endothelium
16-19th week:cytotrophoblast disappear
20th week:CT in villus is less but capillary is more.
action: preventing the large molecular matter into fetal circulation
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5). function: material metabolism
material exchang:
metabolic product from fetus to mother,
nourishment from mother to fetus.
aids virus, heroin,some medicine
secreting hormone:
HCG(human chorionic gonadotropin),3- 12nd week, it can
be examined in urine keep the corpus luteum, HCS(human
chorionic somatomammotropin) secrete from 8th week
Progesterone: secreted by syncytiotrophoblast from 16th
week
Estrone:
(3)afterbirth: be composed of placenta and fetal mebrane
(4)twins
1). concept: there are 2 fetus in a childbirth
2). rate of occurrence: about 1%
3). classification:
①monozygotic twins
cause:2 blastomere (2 placenta,litter in human being)
2 inner cell mass (1 placenta)
2 primitive streak (1 amniontic sac)
feature : same sex
similar as character ,appearance
suit for organic tranplant(graft),no exclude reaction
②dizygotic twins
cause:2 spermotovum(zygot)
feature:same as ordinary brother/sister ,only different birthday
(5)multiple birth:
number: more than 2 fetus in a childbirth
rate: 3 about 1/10000, 4 about 1/1000000, 5 about 1/100,000,000
cause: as twins
(6)conjoined twins
shape:there is a regional connection between twins(chest,cranial ,gluteal
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portion)
cause:primitive streak does not separate completely .
(OVER)
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