Effects of carp hypophyseal homogenate doses, incubation times, and temperatures on carp oocyte maturation and steroidogenesis in vitro.

Ovarian tissue from carp which had received injections of either saline or carp hypophyseal homogenate (chh) 24 hr prior to sacrifice was incubated for 8, 16, or 24 hr at 4, 15, 20, or 25 degrees with 0, 30, 100, or 200 micrograms chh. 17,20 beta-Dihydroxy-4-pregnen-3-one (17,20 beta P) was produced only by chh-primed tissue, but there was no difference between the two groups in production of testosterone, 17-hydroxyprogesterone, or testosterone glucuronide. Production of all steroids was greatest at 20 degrees which also corresponds to the optimal temperature for germinal vesicle breakdown in primed tissue. While yields of testosterone, 17-hydroxyprogesterone, and 17,20 beta P decreased with time, those of testosterone glucuronide tended to increase, suggesting further metabolism to conjugated and/or reduced metabolites. Germinal vesicle migration in control fish, and GVBD in primed fish, showed no change after 8 hr. The results indicate that the induction of both germinal vesicle migration and the potential for synthesis of 17,20 beta P by the priming dose of chh are of primary importance in the induced ovulation of carp.