Localization of immunoreactive androgen in testicular tissue.

Immunohistochemical localization of androgen in the testes of both rat and squirrel monkey has been performed using an antiserum specific to testosterone and certain related androgens. The bound antibodies were visualized by coupling with antigammaglobulin labeled either with fluorescein isothiocyanate or with a horseradish peroxidase-diaminobenzidine technique. The highest concentration of androgen was found in the interstitial tissue but a significant amount was also present in the seminiferous tubules in the layer adjacent to the tubular wall. Very small amounts of androgen were localized in the tubular wall. This restricted localization in the tubules might indicate either de novo synthesis or active uptake of steroids intermediate in the biosynthesis of testosterone in the seminiferous tubules.