We sought to immunohistochemically localize types I, II and III collagen in various regions of the temporomandibular joint (TMJ) in two female rhesus monkeys at different growth stages: juvenile and late-adolescence. In the condylar cartilage, staining for types I and III collagen was weak in the fibrous layer, intense in the pre-cartilaginous layer, and faint in the cartilaginous layer, whereas that for type II collagen was limited to the cartilaginous layer. The glenoid fossa showed moderate

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... taining for type I collagen and weak staining for type II collagen, indicating that this tissue consists of chondroid bone, which is an intermediary between bone and cartilage. TMJ discs showed more intense staining for types I and III collagen in their periphery than in their centers. Staining for type II collagen was not detected throughout the disc. The posterior attachments showed rather weak staining for type I collagen and relatively intense staining for type III collagen. These results suggest that there are regional differences in the phenotypic expression of the three major collagen components in the growing monkey TMJ, which probably provide specific biomechanical resistance.