- See:
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Disorders
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Ligament Healing Characteristics:
- Discussion:
- collagen is the primary structural protein of the body & occurs in bone, tendon, and scar tissue as well as in
cartilage;
- at least nineteen distinct gene products have been identified in humans, for different types of collagen, that differ by amino acid structure of alpha chains;
- Examples of as collagen types I-XII are given below;
- their composition differs slightly in different species, but its general function is the same in all;
-
biosynthesis of collagen
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type I collagen: bone, tendon, skin, menisci
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type II collagen:
- fibrils of type II collagen account for > 50 % of dry wt of cartilage;
- Examples: Articular cartilage and Nucleus pulposus of intervertebral disc
- type II collagen is also found in small amounts in the vitreous gel and in a number of other tissues during early development;
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type III collagen:
- type III collagen is found in small amounts in many tissues in association w/
type I collagen & is major component of large blood vessels; skin
- type IV collagen, one of the nonfibrillar collagens, is a major constituent of all basement membranes;
- type V and VI collagen, articular cartilage (small amounts)
- type VII and VIII collagen, epithelial basement membranes
- type IX collagen:
- these molecules surround the surface of the type-II collagen fibrils and covalently cross-linked to them;
- these molecules may mediates the interaction of type-II collagen with surroundingr extracellular matrix components;
- type X collagen production:
- short-chain collagen found only in the
hypertrophic zone;
- mutations here may cause
Schmid metaphyseal chondrodysplasia;
- associated with matrix mineralization (calcification)
- type XI, also articular cartilage,
- type XII, tendon
- Microscopic Characteristics:
- in different tissues, size of the collagen fibers varies markedly;
- as measured by light microscopy, diameter of tendon fiber may be several hundred microns, whereas in loose connective tissue it may be only 1;
- w/ the electron microscope, finer fibers called fibrils vary from 20 nm to less to 50 or 60 nm;
- arrangement of these fibrils and their size characterize different tissues;
Development of a reconstituted collagen tendon prosthesis. A preliminary implantation study.
Identification of novel pro-alpha2(IX) collagen gene mutations in two families with distinctive oligo-epiphyseal forms of multiple epiphyseal dysplasia.
Stickler syndrome without eye involvement is caused by mutations in COL11A2, the gene encoding the alpha2(XI) chain of type XI collagen.
A type X collagen mutation causes Schmid metaphyseal chondrodysplasia.
