| Abstract: | The steroidogenic activity of human fetal testes during early and midgestation was monitored by analyzing 58 individual fetal testes (aged 6-20 weeks of pregnancy) for endogenous pregnenolone (P5), progesterone, 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone (T) and estradiol. A clear increase in testicular steroid concentrations, especially in those of T and other 3-keto-4-ene steroids, occurred between 8-11 weeks of gestation and reached maximum between 11-14 weeks. The three steroids present in highest concentrations were P5, androstenedione, and T (maximum concentrations, 1.9-2.7 ng/mg wet tissue). The levels of all of the C-19 steroids measured decreased clearly between weeks 14-20 of gestation, whereas those of the C-21 steroids, P5, progesterone, and 17-hydroxyprogesterone, remained relatively high. Our results suggest that the metabolic reactions converting P5 to androgens are activated in the human fetal testis within a short time range between 8-11 weeks of gestation. The increased androgen production is possibly a consequence of increased 3 beta-hydroxysteroid dehydrogenase activity. Testicular androgen production decreases in the beginning of the second trimester of pregnancy, most likely due to a blockade in the C-21 steroid side-chain cleavage. |
