Characterization of the extracellular matrix of the primate temporomandibular joint

The distribution of type I and II collagens, fibronectin and the fibronectinintegrin receptor, tenascin, laminin, link protein, and cartilage-specific glycosaminoglycans was examined in the primate temporomandibular joint complex using an immunohistochemical approach. In general, type I collagen, fibronectin, and the fibronectin-integrin receptor were found to codistribute throughout the joint complex. Immunostaining for these proteins was notably intense in the prechondroblastic and mineralization zones of the articular cartilages of the joint. Tenascin was identified in several structures of the joint, including the articular cartilages, where intense staining was observed in the prechondroblastic and cartilagenous zones. Laminin was detected only in the adventitia of blood vessels located in the attachment tissues of the disc and joint synovium. Cartilage-specific glycosaminoglycans and type II collagen were observed in the cartilagenous zones of the articular cartilages of the mandibular condyle and temporal bone. In addition, immunostaining for cartilage-specific glycosaminoglycans also was detected throughout the extracellular matrix surrounding "chondrocyte-like" cells located in the joint disc. Despite the localization of cartilage-specific glycosaminoglycans in the disc, type II collagen was not detected in this structure. It is suggested that a fibronectin-integrin receptor mechanism may be involved in the regulation of growth of the articular cartilages of the temporomandibular joint.