Metabolism of Testosterone-4- 14C by Hamster Skin and Flank Organ**From the Department of Dermatology, Skin and Cancer unit, Mount Sinai Medical Center, Miami Beach, Florida, 33140

The metabolism of testosterone-4-14C by hamster skin and flank organ was studied; flank organ metabolized more testostrone than an equal weight of adjacent skin. Androstenedione,† androsterone, androstanedione, dihydrotestosterone (DHT), and 3α-androstanediol were identified by chromatography and reverse isotopic dilution as metabolites formed by flank organ. The metabolites of flank organ and general body skin showed identical chromatographic mobilities. Flank organ produced 4 times as much DHT as an equal weight of adjacent skin. The ratio of total 5α-metabolites formed by both tissues was the same as the DHT ratio, indicating that the greater amount of DHT formed is due to greater formation of 5α-metabolites, in general. In contrast, both tissues produced the same amount of 17-ketosteroids from testosterone and had similar DNA contents, suggesting that the observed difference in 5α-reduction was not due to differences in cellularity but to a greater capacity of the flank organ to reduce testosterone. No 3β-hydroxysteroids, the formation of which has been reported in human skin were found