TUNEL-positive apoptotic cells in the postnatal soft diet rat TMJ

Objective:The relationship between apoptosis and proliferating cell nuclear antigen (PCNA) positive cells were unknown the effect of soft diet in rat temporomandibula joint (TMJ), which induces apoptosis of fibroblast, chondroblast and chondrocyte. Methods:They were immnunohistochemically examined to determine the effect of soft diet in rat TMJ. Results:The number of PCNA-positive cells in the soft diet group was lower than that of the hard diet group and was especially low in the calcified zone in rat TMJ from 28- to 56-days. Apoptosis of cell was mainly found in the endochondral ossification layer of the condyle. TUNEL-positive cells were intensively located at the endochondral ossification layer on the anterior region of the condyle beneath the disk on the 28th day rat of the soft diet group. A few apoptotic cells were observed in the synovial membrane and the disk. Conclusion: The different distribution of the apoptosis and PCNA-positive cells and some extracellular matrices reflect the replication process of the TMJ according to different feeding behavior during development.