CONNECTIVE TISSUE

Department of histology, cytology and embryology

2013 medical students

Kharkov National Medical University

CONNECTIVE TISSUE

• Connects other tissueConnects other tissuess, underlies or , underlies or surrounds them. surrounds them.

• Produces and maintains many different Produces and maintains many different intercellularintercellular substances. substances.

• Provides support and nourishment. Provides support and nourishment.

Connective Tissues Classification：

Blood & lymph Connective tissue proper : Loose connective tissue Dense connective tissue Adipose tissue Specialized Reticular tissue

Mucoid tissue Pigment tissue

Cartilage & bone

Note: All Connective Tissues have:

• Common origin -from mesenchyme

•Common structureCells +Extracellular substance•Common similar) functions

• Note: Connective Tissues contain a high ratio of extracellular matrix to cells.

• extracellular matrix is mostly secreted by cells, which are embedded in it.

• extracellular matrix varies for different tissues and provides their structural and functional features.

• Examples : the fluid part of bloodthe hard part of bone, the tough part of fascia, the resilient part of cartilage.

Embryonic Connective Tissue--- Mesenchyme

• Consists of cells and ground substance with reticular fibers

• Gives rise to all types of Connective Tissues

• 11stst group - Fixed cells (intrinsic) group - Fixed cells (intrinsic) – stable – stable population: population:

• 1. fibroblast – main cells, produce fibers 1. fibroblast – main cells, produce fibers • 2. adipocyte2. adipocyte• 3. reticular cell3. reticular cell• 4. pericyte 4. pericyte

5. undifferentiated5. undifferentiated cellscells(adventitial, (adventitial, perivascular – perivascular – stem cellstem cell) )

All arise from All arise from mesenchymemesenchyme..• 6. Pigment6. Pigment cell – is from cell – is from neural crestneural crest..

Connective tissue cells:Connective tissue cells:

• 22ndnd group - Mobile cells group - Mobile cells – are the – are the blood blood

leucocytesleucocytes..

Connective tissue cells:Connective tissue cells:

Fibroblast is fiber forming cell

Mature fibroblast is called fibrocyte.

Adipocytes (fat cells) Adipocytes (fat cells) function as store function as store

house, mechanical support, conservation of body heathouse, mechanical support, conservation of body heat..

Mobile cells = blood leukocytes Mobile cells = blood leukocytes

Macrophage Macrophage

blood blood monocytemonocyte ps

er

ph

lys

Plasma cell B-lymphocytePlasma cell B-lymphocyte

Mast cells = basophilsMast cells = basophils..

• All types of All types of T-lymphocytesT-lymphocytes

• Microphage = neutrophilMicrophage = neutrophil

• Tissue eosinophilTissue eosinophil

Other mobile cells:Other mobile cells:

• Consists of cells and extracellular matrix, including fibers and ground substance.

• Classified:

• as loose or dense

regular or irregular

Connective tissue proper

Classification

• loose – has predominance of ground substance

• dense – has predominance of fibers

• regular – fibers form parallel bundles

• irregular – fibers are disordered

• Loose (Areolar) is always irreguar CT

• Dense:– Dense regular CT– Dense irregular CT

Loose irregular connective tissue (L.I.C.T.)

• Is the most distributed

• it contains blood vessels

The Cells and Fibers of L.I.C.T.

General components of matrix :

1. Fibers and

2. Ground substance – is a gel

containing: • water, salts and

• 3 kinds of molecules containing carbohydrates: – glycosaminoglycan or GAG, – proteoglycans and – glycoproteins

Extracellular matrix (ECM)

• Permeability

• Barrier to the penetration of bacteria

Features of ground substance:

Hylauronidase is an enzyme produced by WBC’s, sperm and some bacteria.

Injection of hyaluronidase can speed the passage of drugs and fluid through the tissue.

Types of C. T. Fibers• Three types of fibers

– Collagen fibers

• Strongest and most

abundant

Tensile strength > steel– Elastic fibers

• “Yellow fibers”

• Long, thin, branching fibers

• Can stretch and recoil

– Reticular fibers

Fine collagenous fibers

Distribution of Connective tissue proper

(CTP ) CTP is widely distributed.

It forms the capsules of organs and thin septa inside them.

It always underlines epithelia.

It contains blood vessels and through its ground substance all nutrients and waste products diffuse between the blood and parenchymal cells of all other tissues and organs.

• Mechanical support

• Protection

• Exchange of metabolites.

• Homeostasis

• Protection against infections

• Repair after injury, plastic function

Connective tissue proper Functions:

Cooperation of blood and connective tissue cells for:

• Local reaction - inflammation

• General immunological reaction

LCT: protection against infections,

noxious agents:

• High regenerative capacity (fibroblast)

• Fibrous scar formation

• NOTE! LCT carries additional functions

Repair after injury, plastic function of LCT

Other types of Connective tissue proper (CTP):

Dense Regular CTP

Dense Irregular CTP

Fibers are predominant elements

Dense Regular Connective Tissue

• Collagen fibers form parallel bundles• fibrocytes

tendons, aponeuroses

Tensile strength in one direction

fibrocyte

Dense Irregular Connective Tissue

• Collagen fibers are irregularly arranged• Tissue can resist tension from any direction• Very tough tissue -- dermis of skin

Fibrocyte

Connective tissue specialised

Adipose:• Location – deep to skin: sides, buttocks, breasts; padding around eyeballs and kidneys

• Function – insulation, mechanical support, stores energy.

Reticular:• Location – spleen, lymph nodes, bone marrow

• Function – supporting framework for haemopoietic organs

•Mucoid: umbilical cord, incompressible

Adipose Tissue