Fibrous connective tissue
In zootomy, fibrous connective tissue (FCT) is a type of connective tissue which has relatively high tensile strength, due to a relatively high concentration of collagenous fibers. Such tissues form ligaments and tendons; the majority of the tissue does not contain living cells, the tissue is primarily composed of polysaccharides, proteins, and water.
The cells of fibrous connective tissue are mostly fibroblasts, irregular, branching cells that secrete strong fibrous proteins as an extracellular matrix. The most commonly secreted protein is collagen which represents one-fourth of all vertebrate protein. Collagen is tough and flexible and gives strength to tissue. Elastin fibres are thinner than collagen fibres and are also secreted by fibroblasts. These protein fibres have longer cross-links than collagen fibres, which gives elastin fibres great elasticity.
There are several categories of fibrous connective tissue:
- Loose connective tissue supports most epithelia and many organs. It also surrounds blood vessels and nerves. It is also found between muscles
- Dense connective tissue has collagen fibres as its main matrix element.
- Elastic connective tissue is primarily composed of elastin fibres, giving them great elasticity. It appears in the walls of the aorta.
- Reticular connective tissue is composed of interlacing fibers of collagen called reticular fibers. This tissue forms supporting structures for many organs, such as the spleen and thymus.