Androgen biosynthesis by marmoset testes in vitro.

These studies were undertaken to determine the major steroid metabolites formed from selected androgen precursors by the testis of the marmoset, Saguinus oedipus, a New World primate of the family Callitricadae. Testicular fragments (50 mg) were incubated for 3.0 hr with pregnenolone-7-³H or with progesterone-7-³H. The major metabolites formed from pregnenolone were 17α-hydroxyprogesterone (42.7%), testosterone (20.5%), androstenedione (11.4%) and progesterone (9.2%). Nonmetabolized substrate was 6.8% of radioactivity. For porgesterone incubations, 17α-hydroxyprogesterone was the major matabolite (49.0%), with testosterone (21.2%) and androstenedione (10.7%) as lesser metabolites. Unreacted progesterone accounted for 14.9% of all radioactivity. The unusually high levels of 17α-hydroxyprogesterone in marmosets is in contrast to that observed in other mammalian species.