[Experimental study of the mechanism of chondroid metaplasia of the bilaminar zone following anterior disc displacement of temporomandibular joint].

Purpose: To investigate the source of the metaplasia chondrocytes in the bilaminar zone following anterior disc displacement (ADD) of temporomandibular joint (TMJ).

Methods: 12 Japanese adult rabbits were randomly divided into A and B groups. Each group contained 4 experimental and 2 control rabbits. The disc of the experimental rabbits was induced forward and fixed into the holes made in the zygomatic arch. Group A was stained by HE and examined for the expression of proliferating cell nuclear antigen (PCNA) and fibroblast growth factor receptor 3 (FGFR3) by immunohistochemical methods. Group B was observed under transmission electron microscopy (TEM).

Results: Chondrocytes appeared in the bilaminar zone of each experimental rabbit. Both PCNA and FGFR3 were positive in part of them. Under TEM, some cells took on the double characters of chondrocyte and fibroblast and some others appeared the characters of naive cells.

Conclusions: Following ADD of TMJ, some metaplasia chondrocytes might be proliferated and differentiated from mesenchymal stem cells.