Chondrocyte apoptosis in temporomandibular joints with disc displacement.
OBJECTIVE
We sought to study the presence of apoptosis in cartilage from rabbit temporomandibular joints with disc displacement (DD), and to examine the relationship between chondrocyte apoptosis and chondrocyte proliferation.


METHODS
Thirty Japanese white rabbits were used in this study. The right joints of 20 rabbits were subjected to surgical DD. Specimens were collected for study at 4 days and 1, 2, 4, and 6 weeks after surgery. Temporomandibular joints were studied by microscopy and in situ detection of apoptosis.


RESULTS
Experimental and sham surgery animals tolerated the surgical procedures well, and 16 of 20 of the surgically displaced discs were successful. A decrease in the number of chondrocytes in articular cartilage was observed after 2 weeks. Apoptotic chondrocytes were abundant in cartilage from DD joints. Apoptotic chondrocytes, most obvious at 1 or 2 weeks after surgery, were mostly found in the proliferative and hypertrophic zones. At 6 weeks after surgery, there were fewer apoptotic chondrocytes, but the cartilage layer was thinner than that of the control.


CONCLUSIONS
This study shows that chondrocyte apoptosis is increased in rabbit DD articular cartilage at early stage and that the apoptotic cells were localized predominantly in the proliferative and hypertrophic zones. Chondrocyte death may be of pathogenetic significance during cartilage repair in response to DD.
Gu
Zhiyuan
Z
Department of Oral and Maxillofacial Surgery, Hospital of Stomatology, Zhejiang University, Hangzhou, PR China. gzy@mail.hz.zj.cn
Shibata
Takanori
T
Cao
Zhiqiang
Z
Feng
Jianying
J
Hu
Ji'an
J
D000818:Animals; D017209:Apoptosis; D002455:Cell Division; D019902:Chondrocytes / Q000473:pathology*; D005260:Female; D006651:Histocytochemistry; D004204:Joint Dislocations / Q000473:pathology; D008297:Male; D011817:Rabbits; D019224:Temporomandibular Joint Disc / Q000473:pathology*; D013705:Temporomandibular Joint Disorders / Q000473:pathology*