Arrangement of D-periodic collagen fibrils and association of proteoglycans with fibrils in the synovium of the mouse temporomandibular joint

The present study was performed to examine changes in the arrangement of D- periodic collagen fibrils in the synovium of the growing temporomandibular joint in mice. At 1 week of age, the mandibular condyle was undeveloped, an d only a few collagen fibrils were recognizable in the subintimal layer of the synovium, At 8 weeks, the mandibular condyle was structurally developed with an increase of collagen fibrils in the synovium; a fully mature condy le was observed at 6 months of age. The close association of proteoglycans with collagen fibrils in the synovium of the growing joint was examined by both conventional and energy-filtering transmission electron microscopy of cupromeronic blue-stained specimens. Proteoglycans were associated with D-p eriodic collagen fibrils in the short filamentous form in random fashion at 1 week of age, but in a regular pattern with D-periodicity at 6 months. Th ese associations in the synovium could be correlated with the mechanical ch aracter of the temporomandibular joint.