title: [Histologic study of the temporomandibular joints after ovariectomy in rats].
abstract: OBJECTIVE
  To investigate histologic changes of the temporomandibular joints (TMJ) after ovariectomy in adult rats.
  
  
  METHODS
  Sixty-eight female SD rats aged twenty weeks were assigned to 2 groups. One group underwent bilateral ovariectomies served as experimental group. The other underwent sham ovariectomy served as control group. The rats were killed at the intervals of 1, 2, 4, 8 and 12 weeks postoperatively. Histologic observation of the TMJ was performed in a synchronous manner by using light microscopy(LM), scanning electron microscopy(SEM) and transmission electron microscopy (TEM). The serum levels of estrogen and bone mineral density of femur were also determined.
  
  
  RESULTS
  In the experimental group, the serum levels of estrogen were obviously decreased, and bone mineral density of femur was significantly decreased at 12 weeks postoperatively. No obvious histological changes of TMJ of rats were observed at 1 and 2 weeks after the ovariectomy, whereas thickness of the condylar cartilage was increased, with irregular shape of chondrocytes at 4 and 8 weeks postoperatively. A serial of degenerative changes in the TMJ was observed in osteoporotic rats at 12 weeks after the ovariectomy.
  
  
  CONCLUSIONS
  Estrogen deficiency in rats may cause alterations of the TMJ, and osteoporosis may predispose to degenerative changes in the TMJ.
authors.affiliation: School of Stomatology, Beijing Medical University, Beijing 100081, China.
authors.forename: P
authors.initials: P
authors.lastname: Cheng
authors.forename: X
authors.initials: X
authors.lastname: Ma
authors.forename: S
authors.initials: S
authors.lastname: Li
mesh_terms: D000818:Animals; D005260:Female; D008854:Microscopy, Electron; D023421:Models, Animal; D010052:Ovariectomy / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000601:surgery; D013704:Temporomandibular Joint / Q000033:anatomy & histology* / Q000648:ultrastructure