Compartmentation of Microsomal Cytochrome P-450 and 17α-Hydroxylase Activity in the Rat Testis

Abstract

The adult testis consists of two functionally different tissue compartments: the interstitial tissue which serves in a hormonal role and the seminiferous tubules which function in a reproductive role. In addition to having dissimilar roles in the testis, the two tissues are also characterized by different functional cell types. The interstitial tissue, which is found interspersed between the seminiferous tubules, contains the steroid-producing Leydig cells; whereas the seminiferous tubules are composed of two cell types, the germinal and Sertoli cells. In recent years, an interest has increased as to whether the latter compartment in the testis, i.e., the seminiferous tubules, can also function in a hormonal or steroidogenic role. Such interest has been fostered particularly by the studies of Lacy and associates (1) who have implicated the Sertoli cells of the seminiferous tubules in an androgen synthetic pathway similar to that found in the Leydig cells. Their evidence is based on studies in which seminiferous tubules separated from interstitial tissue of the rat testis were capable of in vitro synthesis of testosterone from steroid precursors such as pregnenolone and progesterone. Other investigators (2–6) undertaking similar experiments have reported that the seminiferous tubules of the rat testis may account for 10 to 30% of the total testosterone biosynthesis from progesterone.