Connective (or Supporting) Tissues

Two major components of connective tissues:

  1. Cells
  2. Extracellular matrix

1. Cells

Differentiated cells of connective tissue include:

2. Extracellular matrix of supporting tissue

Ground substance

Structural glycoproteins

Fibres

Three main types:
1. Collagen
2. Reticular
3. Elastic

Types I, II and III polymerize to form rope-like fibrils

Type I - provides tensile strength in dense connective tissues of the skin dermis, tendons and ligaments, also loose supportive tissue and bone.
Type II - predominant form in hyaline and elastic cartilage.
Type III - makes up reticular fibres (see below)

Type IV collagen forms a meshwork structure rather than distinct fibrils and is an important constituent of basement membranes.

1. Electron micrograph of a Fibroblast

Types of connective tissues

1.Fibrocollagenous Tissues

Fibrocollagenous tissues are relatively unspecialised tissues (compared to bone and cartilage) and are characterised by significant quantities of collagen fibres (type I usually but also type III) made by fibroblasts.

Fibrocollagenous tissues are classified by:

Several classes of supporting tissue come under this heading:

Fibrocollagenous tissues provide a framework in many tissues and glands, permit transport of materials and act as a form of biological packing material or connection between cells and tissues with more specific functions.

A. Loose or areolar connective tissue

2. Submucosa of large intestine
3. Lamina propria of small intestine (duodenum)

B. Dense connective tissues

4. Dermis of skin
5. Tendon

C. Reticular tissue

6. Liver

2. Adipose tissue

There are two main types of adipose tissue:
7. Breast
8. Brown adipose tissue

3. Cartilage

Varying proportions of collagen and elastic fibres define three main types:

1. Hyaline cartilage (Gk hyalos- glass)

  • is found in articular surfaces of synovial joints, in the respiratory system and as a precursor to bone in the developing skeleton
  • has an amorphous matrix of ground substance reinforced by collagen (usually type II)
  • except in articular cartilage, is surrounded by perichondrium consisting of condensed fibrocollagenous supporting tissue containing chondroblasts with cartilage forming potential

2. Elastic cartilage

  • has a architecture similar to hyaline cartilage
  • has a collagen-containing matrix with an abundant network of elastic fibres
  • is found in the external ear, epiglottis and auditory tube

3. Fibrocartilage

  • is a hybrid tissue between dense fibrocollagenous tissue and hyaline cartilage
  • is found in places including intervertebral disks and in association with dense fibrous tissue in tendons and ligaments
9. Trachea
10. Epiglottis
11. Intervertebral disc

Key concepts:

A typical exam question
The photomontage here shows several different types of connective tissue.
Connect to WebCT for formative assessment.


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