INVITRO STIMULATION OF GERMINAL VESICLE BREAKDOWN AND OVULATION OF YELLOW PERCH (PERCA-FLAVESCENS) OOCYTES - EFFECTS OF 17ALPHA-HYDROXY-20BETA-DIHYDROPROGESTERONE AND PROSTAGLANDINS

The in vitro effects of 17α-hydroxy-20β-dihydroprogesterone (17α-OH-20β-D-PROG), 20β-dihydroprogesterone, and 11-deoxycortisol on germinal vesicle breakdown (GVBD) and ovulation of yellow perch (Perca flavescens) oocytes were investigated. Of the steroids tested 17α-OH-20β-D-PROG was the most effective in inducing GVBD and ovulation. At higher concentrations each steroid induced ovulation and GVBD but these processes were not necessarily synchronized. Therefore, in certain incubates with less mature oocytes (denoted by germinal vesicle position) ovulation occurred prior to GVBD. In general, there was a lower steriod concentration that induced GVBD without ovulation by 48 hr. Longterm incubations revealed that ovulation did eventually occur in incubates with low concentrations of 17α-OH-20β-D-PROG that induced GVBD but not ovulation by 48 hr. Indomethacin blocked in vitro ovulation induced by 17α-OH-20β-D-PROG. Prostaglandins F2α, E1, and E2 (PGE2) all induced ovulation in the indomethacin-blocked follicles but PGE2 was the most effective. © 1979.