Morphologie, Microscopic, and Immunohistochemicai Investigations Into the Function of the Primate TMJ Disc

The distribution and arrangement of extracellular matrix prutetns tvere examined in the primate temporomandibuiar joint disc and posterior attachment using a combination of light microscopic, immunohistochemicai, and biochemical techniques. The band areas of the disc contain a complex collagenous (type I) fiber network consisting of a mediolaterally directed ftber bundle system that interlaces or becomes continuous with an anteroposteriorly directed collagenous fiber array that runs through the intermediate zone. Thin, branching, elastic fibers are a significant component of the disc and are generally oriented parallel to the collagenous fiber network. Interfibrillar spaces in band areas contain numerous chondrocytes encased within a matrix that is rich in a high molecular weight, predominantly chondroitin-sutfate proteoglycan and type a collagen. The intermediate zone appears tendinous in its construction and ts composed of anteroposteriorly oriented elastic and collagenoMS fibers, scattered chondrocytes, and reduced amounts of chondroitin-sulfate proteoglycan and type¡ I collagen. The posterior attachment is composed of fibrocytes, larger caliber elastic fibers, loosely organized type I collagenous fibers, and tow molecular weight dermatan-sulfate proteoglycan. These results indicate that the primate temporomandibuiar joint disc is a microheterogenoiis tissue with distinct regional specializations.