In vitro metabolism of progesterone by the human undescended testis

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Abstract
Testicular biopsy specimens from 28 boys with undescended testis, and from 6 men operated post-pubertally for undescended testis, were incubated in vitro with [3H]progesterone (P). Significant steroid metabolic activity was demonstrated in all biopsies. Before puberty the total conversion rate was low and only a small amount of 17.alpha.-hydroxyprogestrone (17.alpha.-OH-P) was formed. The amount of newly formed 20.alpha.-dihydroprogesterone (20.alpha.-DH-P) was relatively constant regardless of increasing maturity. After puberty the total conversion rate was higher. More 17.alpha.-OH-P was synthesized, and the ratio between formed 20.alpha.-DH-P and 17.alpha.-OH-P decreased significantly. The position of the undescended testis did not appear to influence progesterone metabolism. In no case was deficient steroidogenesis demonstrated. In one 17 yr old boy the 20.alpha.-DH-P/17.alpha.-OH-P ratio was lower in the undescended testis (0.9) than in the scrotal testis (4.0), suggesting increasing steroidogenesis per mg tissue in the malpositioned testis. Since even grossly displaced testes have a relatively undisturbed steroidogenic capability, the reason for impaired descent may not simply reflect disturbed androgen synthesis, but must involve other mechanisms.