CONNECTIVE TISSUE TYPES

CONNECTIVE TISSUEIt is a type of tissue that connect and support other body tissues, also called supporting tissue.CLASSIFOCATION:Classified on the basis of following four criteria1. Relative proportion of various fibers2. Compactness and arrangements of these fibers3. Nature of matrix4. Types of cell present

• On the basis of factors mentioned above connective tissue is grouped into two main categories

1. Embryonal C.T2. Adult C.T

EMBRYONAL C.T

• Developmentally the C.T are derived from mesoderm• Immature C.T derived from mesoderm is called

mesenchyma,it is composed f roughly star-shaped cells.• As the development progress the mesenchyme gradually

assumes the characteristics of adult C.T• The first change is the appearance of fibers and the

embryonal connective tissue of this stage is called mucous tissue.

• The umbilical cord contains considerable amount of mucous tissue which in this location is called warton’s jelly.

ADULT C.T

It is further divided into following three main varieties1. Connective tissue proper2. Cartilage3. bone

Types of Connective Tissue

2:CARTILAGE:

I. Hyaline Cartilage

II. Elastic Cartilage

III. Fibrocartilage Cartilage

3: BONE

A: EMBRYONAL C.T:I. Mesenchyme II. Mucous tissue

B: ADULT C.T1: connective tissue properLoose Connective Tissue

I. areolarII. reticularIII. adipose

DENSE CONNECTIVE TISSUEIV. regularV. irregular

CONNECTIVE TISSUE PROPERClassified into further following two subtypes:

1. loose connective tissue2. Dense connective tissue

1: LOOSE CONNECTIVE TISSUE:• In Loose Connective Tissue, the fibers in the extracellular matrix are

loosely arranged. • Lots of ground substance. • The ground substance is semifluid (viscous). Cells are scattered

throughout the tissue.• Not very cellular.

LOOSE CONNECTIVE TISSUE INCLUDES:I. Areolar Connective TissueII. Adipose TissueIII. Reticular Connective Tissue

LOOSE AREOLAR CONNECTIVE TISSUE

• Areolar is the most abundant type of connective tissue.• All kind of fibers and cells are present.• It is the packing and anchoring material of the body.• It binds other tissues, organ components, and organs together

and allow flexibility and mobility between such parts.• form the supporting frame work (stroma) of most of the

organs.

examples:1. Superficial and deep fascia2. Mesentery3. omentum

LOCATION:1. Found in the subcutaneous layer deep to skin and in

superficial part of dermis2. mucus membranes3. around blood vessels4. nerves and body organs

FUNCTION: supports glandular epithelium and mesothelial layers of mesentery, supports immune cells

RETICULAR CONNECTIVE TISSUE

DESCRIPTION:• R.C.T consists of reticular cells and reticular fibers.• Reticular cells have stellate shape and possess long

processes which pass in different directions to make contact with the neighboring cells.

• The dominant fiber is reticular fiber. • Reticulocytes are fibroblasts that produce reticular fiber . • The ground substance is semifluid.

LOCATION:• Found in lymph nodes and other non-muscular organs• Provides a support structure for macrophages and other

cells involved in immunity.

FUNCTION :• forms the framework (stroma) of liver, spleen,

bone marrow, and lymphoid organs.• Produce reticular fibers• Can also act as phagocytes• May also give rise to precursors of

erythrocytes and leukocytes

ADIPOSE TISSUE

• Consists almost entirely of fat cells arranged into lobules that are separated from each other by fibrous septa.

Depending on its color, location and morphology of component cells, the adipose tissue is subdivided into two verities

1. WHITE OR UNILOCULAR ADIPOSE TISSUE• Widely distributed in the body includes most of the adipose

tissue of adult man.• On naked eye it appears whitish or light yellow in color.• Under L/M fat cells of white adipose tissue shows a single

large fat droplet in the cytoplasm that is why they are called unilocular fat. The fat droplet is not membrane bound.

• These cells give a typical signet ring appearance in ordinary H%E stained sections

ADIPOSE TISSUE

2: BROWN OR MUTILOCULAR ADIPOSE TISSUE• On naked eye it appears brown• The fat cells here have fat in the form of many small droplets

instead of one droplet, that is why they are also called multilocular fat.

• In adult this tissue is absent or restricted in distribution but in fetus and child it is common

The brownish appearance is due to two reasons 1. This tissue has a very rich capillary blood supply2. These cells contain numerous mitochondria and are rich in

cytochrome enzymes which have colored component

ADIPOSE TISSUE

NOTE: as compared to other varieties of connective tissues the adipose tissue consist of cells and not intercellular substance. In other words the cell-intercellular substance ratio is ratio resemble that of the epithelium.

Function: 1. Act as important food reserve of the body and chief site of

energy storage (this function is restricted to white fat)2. Mechanical function of acting as shock absorbing pads, in

buttocks, soles etc.3. Plays important role in temperature regulation which is

accomplished by two following waysI. By heat production as a result of fat metabolism(function of

brown adipose tissue)II. Acting as insulator to prevent heat loss from the body

Dense Connective Tissue

• The extracellular matrix consists of tightly packed parallel bundles of collagen fibers with less cells as compared to loose connective tissue and very little ground substance.

• It is less flexible and far more resistant to stress.According to its arrangement of component fibers it is

divided into two categories1. Regularly arranged dense C.T2. Irregularly arranged dense C.T

REGULARLY ARRANGED DENSE C.T

• Fibers are densely packed and are parallel to each other• Usually occur in the form of cords and bands• Examples: tendons, aponeurosis and ligamentsTendons:• Composed entirely of collagen fibers• Fibers run parallel and closely packed in the form of

bundles separated by a small quantity of intercellular substance.

• Fibroblasts are the only cells present• The whole tendon is surrounded by a layer of

fatty ,coarse connective tissue sometimes called as epithelium

REGULARLY ARRANGED Dense C.T

Apo-neurosis:• Apo-neurosis have the same structure as tendon but these

are broad and relatively thin.• The fibers may be arranged in several superimposed layers,

those of one layer running at an angle to fibers of the adjacent layer.

Ligaments:• Ligaments are bands of dense connective tissue.• Structurally they resemble tendons because they are

predominantly composed of collagenous fibers.• A few ligaments consists entirely of elastic fibers, these are

called yellow elastic ligaments.

IRREGULARLY ARRANGED DENSE C.T

• This variety of C.T occur in the form of sheets.• Consist mainly of collagenous fibers but elastic and reticular

fibers are also present.• The components fibers interlace to form a network.• Fibroblasts and some macrophages are found between the

fibers . Location:• Found in the dermis of the skin• capsule of some organs (liver, testes, lymph nodes) • Fibrous sheaths of cartilage (perichondrium) and bone

(periosteum)

Function: Provides strength and support to organs