Histochemical location of 17 beta-hydroxysteroid oxidoreductase in the adult and infantile human testis.

17 beta-Hydroxysteroid oxidoreductase in the human testis was investigated histochemically using tissues obtained from seven patients with undescended testis or varicocele at the time of orchiopexy or high ligation of spermatic vein. Formazan precipitates were formed from nitro-blue tetrazolium in the tissue utilizing hydrogen released by oxidation of testosterone, which is catalyzed by the reductase function of 17 beta-hydroxysteroid oxidoreductase. The precipitates were formed specifically in the presence of 17 beta-hydroxy-C19-steroids under the conditions employed in the present study. In infantile testes, the precipitates were formed in cytoplasm of immature Sertoli cells, while in pubertal or adult testes, marked formazan precipitates were found in cytoplasm of both Sertoli and Leydig cells. The results indicate the presence of two distinct 17 beta-hydroxysteroid oxidoreductases in the human testis; one in Sertoli cells and detectable independent of age and the other only in functional Leydig cells.