The effects of ovulation induction on ovarian epithelium dysplasia scores and Ki67 expression: an experimental study on rats

We aimed to evaluate the effects of ovulation induction on Ki67 expression and dysplasia scores of female rat ovaries. Twenty female Wistar rats were randomized either to receive 150 IU/kg human menopausal gonadotropin on estrous day 2 and 75 IU/kg human chorionic gonadotropin on the day of preestrous (induction group, n = 10) or saline as placebo on the corresponding days (control group, n = 10). After five estrous cycles bilateral oophorectomy was performed to compare the Ki67 expression and dysplasia score of the ovarian epithelium. The mean number of the cells that stained positive for Ki67 was 159.6 +/- 101.92 in the follicles, 283.4 +/- 42 in the corpus luteum, and 151 +/- 75.1 in the stroma of the study group compared to 41.8 +/- 35.6 (P= 0.03), 43.2 +/- 28.3 (P = 0.007), and 55.6 +/- 18.6 (P = 0.01), respectively, in the control group. The mean number and rate of cells that stained positive for Ki67 in the epithelium was significantly higher in the ovulation induction group (758 +/- 71 and 63 +/- 1.6%, respectively) compared to the control group (386 +/- 23, P < 0.001; and 60 +/- 1.1%, P < 0.001; respectively). The mean dysplasia score was significantly higher (9.6 +/- 1.3) in the study group compared to the control group (5.08 +/- 0.9, P < 0.001). Ovulation induction in rats resulted in increased Ki67 expression and dysplastic features in the ovarian epithelial cells.