The age-related expression of the extracellular matrices in human mandibular condyle was examined.
The distribution patterns of types I to V collagens, laminin, fibronectin, fibronectin receptor, and transforming growth factor beta in 34 human mandibular condyles dissected from autopsy specimens were studied by immunohistochemical procedure with special attention on the age-related changes.
Type I collagen was detected in the full layer of the condylar cartilage, and a stronger immunoreaction was delineated in the articular and cartilage zone. Types II and III collagen were mainly localized in the fibrocartilage zone. Type IV collagen and laminin were detected not only in the basement membrane of the blood vessels but also in the degenerated lesion where the expression of transforming growth factor beta was also detected. Immunostaining of type V collagen and fibronectin was noted in the perichondrocytic area, whereas that of fibronectin receptor was seen in the chondrocytes. In materials from younger cadavers types I, II, IV and V collagens, fibronectin, its receptor, and laminin showed stronger expression in the degenerative lesions than in the normal portions. In the sections from cadavers over the seventh decade, the immunoreaction of extracellular matrices was weak compared with the younger materials, and no increased reaction of extracellular matrices in the degenerative lesions was detected. In addition, severe osteoarthrosis was frequently seen in the older materials in macroscopic findings.
These results suggest that the expression of extracellular matrices thus seems to be closely related to aging and degenerative changes in the condyle.