Oocytic meiosis in cultured rat follicles during inhibition of steroidogenesis.

Steroid release by cultured Graafian follicles explanted from rat ovaries on the morning of pro-oestrus was measured by radioimmunoaso the medium reduced the basal level of steroid secretion (progesterone, androstenedione and oestradiol-17beta) and abolished the steroidogenic effect of luteinizing hormone (LH; 5mug/ml) and prostaglandin E2 (PGE2; 10 mug/ml). However, the induction of oocyte maturation by either LH or PGE2 was not impaired by total suppression of the steroidogenic response of the follicles to these hormones by cyanoketone or aminoglutethimide. It is concluded that the meiosis-inducing action of LH on the mammalian egg is not mediated by the effect of the hormone on the rate and pattern of follicular steroidogenesis.