Leydig cell function in the absence of an intact Y chromosome

Sex-reversed mice (X/X Sxr) provide a unique opportunity to study Leydig cell function in the absence of an intact Y chromosome. We determined the impact that the absence of an intact Y chromosome has on Leydig cell function by comparing the steroid secretion profiles of in vitro perfused testes from X/X Sxr and X/Y mice. All the testes were maximally stimulated with luteinizing hormone (LH). Nine steroids were extracted from the venous effluent of the in vitro perfused testes and quantified by capillary gas chromatography. A radioimmunoassay was employed to determine the estradiol secretion rate. Secretion rates (ng/h . testis) of seven steroids, including testosterone, did not differ significantly. Testes from X/X Sxr mice secreted more (P less than 0.05) dehydroepiandrosterone and androstenedione than X/Y mouse testes. Importantly, X/X Sxr and X/Y mouse testes secreted the same total amount of steroids, although X/X Sxr mouse testes weigh 17 mg while X/Y mouse testes weigh 110 mg. Histological studies established an increase in the relative mass of Leydig cells and the complete absence of germ cells in X/X Sxr mouse testes. The results suggest that the normal differentiation of steroidogenic pathways occurs in X/X Sxr mouse tests in the absence of an intact Y chromosome.