Connective tissue is a widely distributed general type of tissue that supports, binds and protects the special (well-differentiated) tissues of the body.
It has both the cellular and extracellular components.
The cellular component of connective tissue plays the role of active defense, whereas the extracellular component (fibers and ground substance) serves a number of mechanical functions of support and protection against the mechanical stresses and strains.
The ordinary type of connective tissue is distributed all over the body, but the special type of connective tissue forms certain well-differentiated tissues, like the bone and cartilage.
The greater part of connective tissue develops from embryonic mesoderm.
A number of cell types are also found in the connective tissue the blood and lymph.
the cells of the connective tissue are widely separated by the abundance of the extracellular matrix.
Following are types of Connective Tissue:-
Different types of connective tissue are found in different parts of the body according to the local functional requirements. These types are based on the predominance of the cell type, concentration, and arrangement of the fiber type, and character of ground substance. The connective tissues are classified as follows.
I. loose Connective Tissue
Its types are Areolar tissue, adipose tissue, myxomatous tissue, and reticular tissue.
ll. Dense Irregular Connective Tissue
2. Specialised-cartilage and bone.
The details of cells, matrix, and types of connective tissue are described in the Histology, 5th edition by K Garg, I Bahl and M Kaul.
Functions of Connective Tissue
1. As a packing material, connective tissue provides a supporting matrix for many highly organized structures.
2. It forms a restraining mechanism of the body in the form of retinacula, check ligaments (Fig.9.1) and fibrous pulley (Fig.9.2).
3. The ensheathing layer of deep fascia preserves the characteristic contour of the limbs and aids circulation in the veins and lymphatics.
4. It provides a surface coating of the body in the form of superficial fascia which stores fat and conserves body heat.
5. It provides additional surface for the attachment of muscles in the form of deep fascia, intermuscular septa, and interosseous membranes.
6. It forms fascia] planes that provide convenient pathways for vessels (blood vessels and lymphatics) and nerves.
7. In places where it is loose in texture ( loose connective tissue), it facilitates movements between the adjacent structures, and by forming bursal sacs it minimizes friction and pressure effects.
8. Connective tissue helps in the repair of injuries whereby the fibroblasts lay down collagen fibers to form the scar tissue.
9. The macrophages of connective tissue serve a defensive function against the bacterial invasion by their phagocytic activity. They also act as scavengers in removing the cell debris and foreign material.
The plasma cells are capable of producing antibodies against specific antigens (foreign proteins). The mast cells, by producing histamine and serotonin, are responsible for the various inflammatory, allergic and hypersensitivity reactions.
Pigment cells protect the skin against ultraviolet radiation so that the inflammatory changes typical of sunburn do not occur, and the chromosomal damage in the dividing cells of the epidermis is avoided.
10. Connective tissue contains mesenchymal cells of embryonic type. These are capable of transforming into various types of connective tissue cells with their discrete functions.