Fig. 3.
Musculoskeletal joint tissues. A. Articular cartilage is comprised of a network of collagen II and a high density of aggrecans. Collagen fibrils are aligned parallel to the surface in the superficial zone (SZ) while arranged perpendicularly in the cartilage deep zone (DZ); aggrecan density increases from SZ to DZ. B. Synovial fluid is comprised of high molecular weight hyaluronic acid meshwork. C. Ligaments and tendons are comprised of linearly aligned collagen I fibrils containing decorin, aggrecans and versicans. D. Meniscus is comprised of circumferentially aligned collagen fibrils, mainly type I in the outer two-third region and a combination of types I and II in the inner region. Aggrecan density is highest in the inner region and decreases towards the outer region. E. Intervertebral disc is comprised ofgelatinous nucleus pulposus containing a random network of collagen II and proteoglycans.