Ovulation induction and endometrial steroid receptors.

The endometrial morphology, endometrial steroid receptors and serum steroid hormone concentrations have been studied in 22 infertile women participating in an in-vitro fertilization, gamete intra-Fallopian transfer programme, including nine cases following treatment with gonadotrophin-releasing hormone analogue/human menopausal gonadotrophin/human chorionic gonadotrophin. All patients had normal ovulatory function before treatment and satisfactory response to ovulation induction. Endometrial biopsies were taken in spontaneous and treatment cycles on the fourth day after ovulation had been detected by ultrasound scanning, when endometrial receptors were measured using immunohistochemistry. Histological examination of biopsies in spontaneous cycles showed the majority (20/22) to be 'in-phase', while in two cases luteal phase defect was diagnosed. After ovulation induction, all the biopsies were still morphologically 'in-phase', although a significant reduction had occurred in the nuclear receptor level in both the glands and stroma for both progesterone receptors (gland P = 0.030, stroma P = 0.012 using microscopic analysis; gland P = 0.020, stroma P < 0.001 using a cell analysis system) and oestrogen receptors (gland P = 0.017, stroma P = 0.002 using direct microscopic analysis). This suggests that a reduction in steroid receptors in the endometrium occurs after ovulation induction in the presence of supraphysiological amounts of steroids, which is not associated with detectable morphological changes.