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Connective Tissues

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Connective tissues

Introduction Connective tissues provide structural support for other tissues

and organs. Connective tissues serve to connect other tissues together. Connective tissues carry blood vessels and mediate the exchange

of nutrients and waste products between tissues and the circulatory system.

Common characteristics The connective tissue cells do not rest on a basement membrane. Connective tissues have two major components: Cells extracellular material

matrix (ground substance) of organic materials. a variety of fibers.

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Connective tissues

The cells of connective tissue The cells of connective tissue can be divided into three types

according to their basic function:1. Cells responsible for synthesis of the extracellular material. These

cells are termed fibroblasts.2. Cells responsible for the storage of fat. These cells are known as

fat cells or adipocytes.3. Cells responsible for defence.

Fibers of connective tissueConnective tissue fibers are synthesized by fibroblasts. They are: Collagen

forms strong bundles which provide strength to the connective tissue. Elastin

rubber-like branching fibers which form an irregular network. Reticulin

branching collagen fibers that form network.

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Connective tissues

Classification of connective tissuesConnective tissues are classified according to the nature of the extracellular matrix as follows:1. Proper connective tissue

The extracellular (intercellular) matrix is viscous fluid. e.g. loose and dense connective tissues

2. Skeletal connective tissue The extracellular matrix is jelly-like or solid. e.g. cartilage and bone

3. Vascular tissue The extracellular matrix is fluid e.g. blood

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Connective tissues

Proper connective tissuesType and abundance of fibers and cells determine the kind of connective tissue.1. Loose (Areolar) connective tissue The fibers are loosely arranged leaving small spaces between

them. Collagenous fibers, also called white fibers, are arranged in wavy

branched bundles, the individual fiber in the bundle does not branch.

Elastic fibers, also called yellow fibers, are thin, branched and singly arranged (do not form bundles).

Cells of loose connective tissue include fibroblasts (synthesize fibers), defence cells (macrophages, mast cells, plasma cells, blood cells) and storage cells (fat cells, also called adipocytes).

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Connective tissues

Proper connective tissues1. Loose (Areolar) connective tissue

Loose (Areolar) connective tissue

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Connective tissues

Proper connective tissues1. Loose (Areolar) connective tissue

Plasma cell

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Connective tissues

Proper connective tissues2. Dense irregular connective

tissue (fibrous C.T.) The tissue is more fibrous and

less cellular than loose C.T. It is formed mainly of collagen

fibers. Collagen fibers are arranged

irregularly assuming a network appearance.

Found in the dermis of skin.Dense irregular connective tissue (fibrous C.T.)

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Connective tissues

Proper connective tissues3. Dense regular connective tissue

(fibrous C.T.) Collagen fibers are abundant

and are arranged in parallel bundles.

Found in tendons and ligaments.

Dense regular connective tissue (fibrous C.T.)

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Connective tissues

Proper connective tissues4. Elastic connective tissue Elastic fibers predominate. Provides elastic properties which

enable recovery of tissue shape following stretching.

Found in arteries, lungs.

Elastic connective tissue

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Connective tissues

Proper connective tissues5. Mucous connective tissue It is formed of a network of

interconnecting fibroblasts embedded in an abundant jelly-like matrix.

It contains few and short fibers of collagenous type.

Found in umbilical cord.

Mucous connective tissue

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Connective tissues

Proper connective tissues6. Adipose connective tissue It is composed of groups of fat cells. Found in the subcutaneous tissue and around some organs.

Adipose connective tissue