THE IN VITRO FORMATION OF ANDROSTENEDIONE FROM C21 STEROIDS BY FOLLICLES ISOLATED FROM HUMAN OVARIES

ABSTRACT Follicles from human ovaries were incubated simultaneously with [4- 14 C] pregnenolone and [7α- 3 H] progesterone in 3 experiments. Samples of the incubation medium were withdrawn at 10, 30 and 60 min and the incubation stopped at 180 min. The unchanged substrates, 17-hydroxyprogesterone, dehydro epi androsterone and androstenedione were isolated from each sample. 17-Hydroxypregnenolone was also isolated in one experiment. The product yield-time curves and the 3 H/ 14 C ratios of compounds isolated at different time periods showed that in the formation of androstenedione from pregnenolone the following pathways can be operative in the follicle; 1) the Δ 5 pathway passing through 17-hydroxypregnenolone and dehydro epi androsterone, 2) the pathway passing through 17-hydroxypregnenolone and 17-hydroxyprogesterone and 3) the Δ 4 pathway passing through progesterone. Of these, the first two were found to be of major importance.