Metabolism of androgens in vitro by human foetal skin.

Fresh scalp, genital, chest and axillary skin from human foetuses of 12-41 weeks' maturity was incubated in Krebs improved Ringer I medium with (7alpha-3h)dehydroepiandrosterone, (7alpha-3H)testosterone and (7alpha-3H)androstenedione. The metabolites identified were androstenedione, 5alpha-androstane-3alpha, 17beta-diol, 5alpha-androstane-3beta, 17beta-diol, 5-androstene-3beta, 17beta-diol and testosterone. The results provide evidence for the presence of 3beta-hydroxysteroid dehydrogenase, delta4-5 isomerase, 17beta-hydroxysteroid dehydrogenase, delta4-3-oxosteroid-5alpha reductase and 3alpha-hydroxysteroid dehydrogenase in human foetal skin. There were quantitative differences in the various enzyme activities between different body sites and skin specimens of different gestational age. 5alpha-Reductase activity was particularly high in genital skin. 3beta-Hydroxysteroid dehydrogenase delta4-5 isomerase activity was low in skin from a 12-week foetus, but high in skin specimens from 28-, 38- and 41-week foetuses. 17beta-Hydroxysteroid dehydrogenase activity was already high in the skin of the 12-week foetus and remained so in the older foetuses. These results were correlated with the development of the foetal sebaceous glands, and were in general agreement with a parallel enzyme histochemical study. The role of androgen metabolism in human foetal skin is discussed.