Leydig Cell Function in the Absence of an Intact Y Chromosome

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Abstract
Sex-reversed mice (X/X Sxr) provide a unique opportunity to study Leydig cell function in the absence of an intact Y chromosome. The impact that the absence of an intact Y chromosome has on Leydig cell function was examined 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 [pregnenolone, dehydroepiandrosterone (DHA), androstenediol, progesterone, androstenedione (DIONE), testosterone, dihydrotestosterone (DHT), 3.alpha.-androstanediol and 3.beta.-androstanediol] 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 per testis) of 7 steroids, including testosterone, did not differ significantly. Testes from X/X Sxr mice secreted more (P < 0.05) DHA and DIONE 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 normal differentiation of steroidogenic pathways occurs in X/X Sxr mouse testes in the absence of an intact Y chromosome.