title: Stereological study of the effects of letrozole and estradiol valerate treatment on the ovary of rats.
abstract: OBJECTIVE
  Letrozole and estradiol valerate are used to treat some hormonally-responsive symptoms and also in modeling of the polycystic ovary syndrome. However, the stereological analysis of the ovary has received less attention. Estimation of the whole ovary volume using the Cavalieri method can be applied in any orientation desired, but estimation of the mean volume of the oocytes requires isotropic uniform random sectioning. Here, a combined method was developed for estimating the parameters. To our knowledge, no comparison has been made of the effects of letrozole and estradiol on the ovary.
  
  
  METHODS
  Sixty rats were divided into 4 groups receiving estradiol (4 mg/kg), olive oil, letrozole (1 mg/kg), or normal saline. After 21 days, their ovaries were studied.
  
  
  RESULTS
  Relative to the control group, the total volume of the ovary and the cortex increased in the letrozole-treated and estradiol-treated rats. In addition, the number of the preantral, antral, and granulosa cells decreased by 43% to 56% in the letrozole- and estradiol-treated rats. On average, a 19% increase was observed in the atretic oocytes of the letrozole-treated and estradiol-treated rats, but the mean oocyte volume decreased by 29% to 44% in letrozole- and estradiol-treated rats. Furthermore, the letrozole-treated rats showed a 5-fold and 7-fold increase in the volume of the cysts and corpus luteum, respectively. A 3-fold increase was found in the volume of both the cysts and corpus luteum in the estradiol group.
  
  
  CONCLUSIONS
  The structural changes of the ovary were most pronounced in the letrozole-treated animals.
authors.affiliation: Histomorphometry and Stereology Research Centre, Shiraz University of Medical Sciences, Shiraz, Iran. ; Anatomy Department, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Noorafshan
authors.forename: Maryam
authors.initials: M
authors.lastname: Ahmadi
authors.forename: Seyed-Fakhroddin
authors.initials: SF
authors.lastname: Mesbah
authors.forename: Saied
authors.initials: S
authors.lastname: Karbalay-Doust
keywords: Histology; Oocyte, Ovary; Rats