Emergence of ovarian 11-deoxycorticosteroid biosynthesis at ovulation time in the sea bass, Dicentrarchus labrax L

Steroidogenesis in the ovary of the teleost Dicentrarchus labrax has been studied in vitro at five different stages : 1) previtellogenic ; 2) postvitellogenic ; 3) postovulatory, one day after HCG-induced spawning ; 4) postovulatory, 9 days after induced spawning ; 5) atretic. Ovarian tissues were incubated with [4-14 C] pregnenolone and (4-14 C] progesterone for 6 hr at 15-16 !C. The following metabolites were formed after ovulation : progesterone (from pregnenolone), 11-deoxycorticosterone, 11-deoxycortisol, 17a-hydroxyprogesterone, androstenedione, testosterone and estradiol-17p. Percentages of conversion were high for 11-deoxycorticosteroids and androgens and low for estradiol-17P. Before ovulation, yields of androgens were high at stage 2 but negligible at stage 1. Estradiol-17p and 11-deoxycorticosterone were obtained in small amounts at maturity but could not be detected during quiescence. Atretic ovarian tissue converted pregnenolone to progesterone but it went no further in steroid hormone biosynthesis.