RU486 INHIBITS OVULATION, FERTILIZATION AND EARLY EMBRYONIC-DEVELOPMENT IN RABBITS - IN-VIVO AND IN-VITRO STUDIES

Objective: To clarify the role of P in ovulation, fertilization, and early embryonic development using RU486, a potent P receptor blocker. Design: Ovulatory efficiency, IVF, and early embryonic development were evaluated after RU486 administration in vivo and in vitro. Setting: Research laboratory of a university hospital. Participants: Mature male and female New Zealand white rabbits. Interventions: Animals were treated with RU486 or vehicle for 3 days before hCG-induced ovulation. Ovaries treated with hCG to induce ovulation were perfused for 6 hours in vitro with RU486 or vehicle. In vitro fertilization was performed in the presence or absence of RU486. Main Outcome Measures: The percentage of mature follicles ovulating (ovulatory efficiency) was determined after in vivo and in vitro treatment. Fertilization, morula, and blastocyst development were evaluated every 24 hours for 120 hours. Results: RU486 significantly inhibited ovulation, fertilization, and early embryonic development. Conclusions: Progesterone plays a significant role in ovulation, fertilization, and preimplantation embryonic development.