Human reproduction
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Following an ovulatory control cycle, six women took 2 mg of mifepristone daily for 30 days. Endometrial biopsies were collected in the control cycle between 7 and 11 days after the plasma luteinizing hormone (LH) surge and on the corresponding day of the treatment cycle (days 19-28). In order to investigate the effects of unopposed oestrogen on the endometrium, persistent proliferative endometrium was obtained from six women with anovulatory infertility due to polycystic ovarian syndrome (PCOS) on a similar cycle day (days 21-23) following a progestogen-induced withdrawal bleed. ⋯ Although PCNA and Ki67 immunostaining were also present in mifepristone-treated endometrium from subjects who did not ovulate, there were no mitoses and significantly less ER immunostaining in spite of exposure to unopposed oestrogen for a similar duration. Since PCNA and Ki67 detect cells throughout all stages of the cell cycle this would suggest that mifepristone might affect the entry of cells into the mitotic phase of the cell cycle and, therefore, might prevent endometrial hyperplasia. These findings add further evidence to support the contraceptive potential and antiproliferative activity of daily low dose mifepristone.