Connective tissue Elastic fibers Notes Collagen fibers Notes

Connective tissue • Elastic fibers Notes • Collagen fibers Notes • Adipose tissue Notes Index

Notes Elastic fibers

Notes Collagen fibers

Notes Adipose tissue Fat locule Peripheral nucleus Adipocyte

Connective tissue: Connective tissue consists of cells and extra cellular matrix. Following are the cells found in the loose ordinary connective tissue. 1. Stem mother cells: These are undifferentiated mesenchymal cells. They have potentiality to differentiate into different cells of connective tissue. 2. Fibroblasts: These are flattened or irregular in outline with large nuclei. They have multiple processes. They produce collagen and elastic fibers and also intercellular substance. Resting, nonfunctional fibroblasts are called fibrocytes.

3. Macrophages: Round or irregular shaped cells with small nuclei found in loose connective tissue and haemopoietic tissue. They are phagocytic in function. 4. Mast cells: These are rounded or oval cells with many filopodia and small centrally placed nuclei. They contain and secrete heparin, histamine and serotonin. These cells are found in the connective tissue, along the blood vessels and in peritoneal fluid. 5. Plasma cells: These are oval cells with peripherally placed cart-wheel like nuclei. They produce antibodies against antigens and are found in highly cellular connective tissues like lamina propria of gastro intestinal tract and respiratory tract, lymphoid tissues and haemopoietic tissue.

6. Fat cells: These are large oval or rounded cells with very little cytoplasm and peripherally placed nuclei. The central large area of the cell is called locule and it contains fat droplets. It is found mainly in adipose tissue. 7. Pigment cells (melanocytes): These cells are found in the epidermis of the skin. They are responsible for the colour of the skin. They protect skin against the harmful effects of sunrays.

Connective tissue fibers: 1. Elastic fibers: Fibers run singly. They branch and join frequently. Cut ends of the branches usually retract and curl. They are made up of a protein called elastin and they look yellowish when fresh. Eg. - Ligamentum flavum, ligamentum nuchae and large arteries. 2. Collagen fibers: Collagen fibers are produced by fibroblasts and are seen in all types of connective tissue. They are made up of fibrils which seen in various bundles and the bundles split into branches. Individual fibers never branch.

Biochemically collagen fibers are made up of a protein called collagen and look white when fresh. Eg: deep fascia, superficial fascia 3. Reticular fibers: These are fine branching fibers, which form a supportive network in organs like lymph nodes and spleen. Ground substance: It is made up of water, carbohydrates and proteins. Carbohydrates are in the form of muco-polysaccharides either sulphated or non-sulphated, in combination with hyaluronic acid. Proteins are in the form of glycoproteins.