Inhibition of Δ5-3β hydroxysteroid dehydrogenase activity in pre-implantation mouse embryos and their implantation by sheep ovarian follicular fluid peptide

Abstract. The activity of Δ5-3β hydroxysteroid dehydrogenase (Δ5-3β HSD) in pre-implantation mouse embryos was inhibited following their prior incubation with partially purified sheep ovarian follicular fluid peptide (OFFP). OFFP, 5 μl, injected into the uterine lumen of day 4 pregnant mice impaired the ensuing implantation of embryos. Our observations suggest that OFFP may inhibit steroid metabolizing activity in pre-implantation embryos and thereby interfere with the process of implantation.