The conversion of testosterone to 5 alpha-androstan-17 beta-ol-3-one (dihydrotestosterone) by skin slices of man.

The conversion of testosterone-1,2-(3)H to dihydrotestosterone by slices of human skin obtained from various anatomical sites in 112 normal subjects and three individuals with the syndrome of testicular feminization has been measured under standardized conditions. Very low rates of dihydrotestosterone formation were observed in sites obtained from the mons or from miscellaneous areas of the trunk and limbs of the control subjects. The mean rates of conversion were very high, however, in slices of skin obtained from several perineal sites (labia majora, scrotum, prepuce, and clitoris). Furthermore, as measured here, the rate of dihydrotestosterone formation by prepuce rises during the 3 months after birth and then falls progressively thereafter, reaching a level in the adult that is almost as low as that observed in the slices of nonperineal skin from all ages. In the patients with testicular feminization dihydrotestosterone formation by slices of skin obtained from the mons was within the normal range, whereas the rates observed in labia majora were lower than the average values obtained in the normal subjects.