Studies on the Mechanism of Action of Estradiol in Regulating Follicular Progesterone Levels: Effects on cAMP Mediated Events and 3β-Hydroxysteroid Dehydrogenase: (ovarian steroidogenesis/cAMP, 3β-hydroxysteroid dehydrogenase/progesterone/estradiol regulation/Rana pipiens).

Previous studies demonstrated that estradiol interferes with pituitary-induced progesterone production and oocyte maturation in cultured amphibian (Rana pipiens) ovarian follicles. To elucidate the mode of action of estradiol in modulating follicular progesterone accumulation we have examined its effects on cAMP-induced progesterone production and enzymatic conversion of pregnenolone to progesterone by 3β-hydroxysteroid dehydrogenase (3β-HSD). Follicular cAMP levels were manipulated with forskolin (an adenylate cyclase activator), isobutyl methyl xanthine (IBMX-phosphodiesterase inhibitor) and exogenously added cAMP.

In-vitro Production of Meiosis Inducing Substance (MIS) by Isolated Amphibian (Rana pipiens) Follicle Cells*: (oocytes/meiosis/steroids/follicle cells).

Previous studies indicated that pituitary hormone induced oocyte maturation in preovulatory amphibian ovarian follicles is mediated by somatic elements of the follicle. In this study procedures were developed for isolating and culturing follicle cells and their ability to produce meiosis inducing substance (MIS) was assessed. Defolliculated oocytes surrounded by a single layer of follicle cells but not denuded oocytes matured in response to frog pituitary hormone (FPH) stimulation.