Testicular steroidogenesis in the Cebus monkey throughout postnatal development.

There is scant information on testicular steroidogenesis during postnatal development in monkeys, particularly in New World species. Our purpose was to study the in vitro steroidogenic capacity of the Cebus monkey testis from birth to advanced puberty. Fresh testicular tissue was incubated in Medium 199 with or without hCG (10 IU/ml); and levels of pregnenolone (P5), dehydroepiandrosterone (DHA), progesterone (P4), androstenedione (A), testosterone (T), dihydrotestosterone (DHT), and 3 alpha-androstanediol (3 alpha-DIOL) were measured in tissue and incubation media by RIA. To determine the predominant steroidogenic pathway, the ratio between the concentrations of the 5-ene and the 4-ene T precursors was determined, and the relative conversion of 3H-P5 and 14C-P4 to T was calculated. The number of Leydig cells per testis was determined in all experimental groups. The testes of the Cebus monkeys could produce T in vitro without the addition of gonadotropins at all ages. T and the 5-ene precursors (P5 and DHA) were the main steroids found within testicular tissue throughout postnatal development. T content per Leydig cell increased continuously with age, but testicular T concentration reached maximal levels at early puberty and did not change thereafter. The ratios between 5-ene and 4-ene T precursors ranged between 2.8 and 13.2, which suggested a predominance of the delta-5 pathway. This was confirmed by the finding that 3H-P5 was more efficiently converted to T than was 14C-P4. The T production relative to that of its d-ene precursors progressively increased to reach maximal values in late puberty.(ABSTRACT TRUNCATED AT 250 WORDS)