An immunohistochemical and in situ hybridization study of the expression of tenascin in synovial membranes from human temporomandibular joints with internal derangement.

In samples of 27 human temporomandibular joints (internal derangement, ankylosis and control specimens) the distribution of immunoreactive tenascin was restricted to the walls of blood vessels, at the perineurium, and at the surface of the disc. Tenascin staining was intense in the stroma of hypertrophic synovial membranes, particularly on the surface of severely hypertrophic synovial membranes with inflammation, proliferation, irregular lining structures and new capillary growth. In situ hybridization of fresh discs and synovial membranes demonstrated that synovial cells as well as fibroblasts and endothelial cells expressed tenascin mRNA. The expression of tenascin mRNA was most evident in synovial cells. It is concluded that synovial cells in the synovial membrane produce tenascin in the diseased human temporomandibular joint.