This immunocytochemical study revealed the expression of caveolin-1, a major protein of caveolae, in the rat temporomandibular joint. In the synovial lining layer, immunoreactive products for caveolin-1 were detected on the cell membrane of the fibroblast-like type B cells, as confirmed by immunocytochemistry for heat shock protein 25. The cells in the articular disk, the articular layer, and zone of proliferation of the mandibular condyle also showed intense immunoreactions for caveolin-1. (C) 2005 Wiley-Liss, Inc.