Effect of temperature, 17 alpha-hydroxy-20 beta-dihydroprogesterone and prostaglandin F2 alpha on carp oocyte maturation and ovulation in vitro.

Two series of experiments were carried out. In series I, studies were conducted on the effect of 17 alpha-hydroxy-20 beta-dihydroprogesterone (17 alpha 20 beta P; 1 microgram/ml of substrate) on the migration of germinal vesicle (GV) and its breakdown (BD) in the oocytes of carp ovarian fragments, kept at 5, 10, 15, 20, and 25 degrees C. For investigations ovarian fragments were taken both from intact mature females and from those injected with carp hypophysial homogenate (chh) at a dose of 1 mg/kg. It was found that GV migration and GVBD occurred at 15-25 degrees C. Based on the results obtained, it appears that GV migration proceeds optimally at 15 degrees C, whereas GVBD requires higher temperatures (20-25 degrees C), although at times it may also take place at 15 degrees C. In series II, studies were conducted on the effects of exogenous prostaglandin F2 alpha (PGF2 alpha) on carp oocytes ovulation in vitro in the ovarian fragments kept at 5, 10, 15, 20, and 25 degrees C for 24 and 48 hr. It was found that the temperatures in the range studied had no statistically significant effect on the ovulation process induced in vitro by exogenic PGF2 alpha added to the medium. The mechanisms of the final stage of carp oocytes maturation and ovulation are discussed.