Activin A stimulates meiotic maturation of human oocytes and modulates granulosa cell steroidogenesis in vitro

Objective: To test the hypothesis that activin A promotes in vitro human oocyte meiotic maturation while inhibiting steroid secretion by nonluteinized antral granulosa cells. Design: Prospective randomized controlled study. Setting: A university medical center. Patient(s): Nine women ranging in age from 31-44 years who were undergoing oophorectomy for nonovarian pathology. Intervention(s): Analysis of meiotic maturation of oocytes and steroid secretion by granulosa cells cultured in the presence or absence of activin A. Main OUtcome Measure(s): Germinal vesicle breakdown (GVBD) and attainment of metaphase II (MII) in oocytes, and progesterone and E₂ secretion by granulosa cells. Result(s): Activin A significantly enhanced GVBD (91% vs. 65%) for control and maturation to MII (56% vs. 35% for control) of immature oocytes. Activin A significantly suppressed basal, and inhibin A-and FSH- stimulated progesterone and E₂ secretion by nonluteinized granulosa cells. Conclusion(s): Activin A is a promoter of oocyte maturation in vitro and a modulator of granulosa cell steroidogenesis in culture.