Hyperactivation of early steps of spermatogenesis compromises meiotic insufficiency in men with hypergonadotropism. A possible quantitative assay for high FSH/low testosterone availabilities

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Abstract
It has been shown previously that blood plasma elevation of FSH is associated with an impaired function of the seminiferous tubules. In the study presented here quantitative analysis of the seminiferous epithelium was performed in testicular biopsies of men with qualitatively complete spermatogenesis and hypergonadotropism (HG group, n = 6) or normogonadotropism (NG group, n = 9). Hormonal determinations were performed also in eight men with Sertoli cells only (SCO group). Plasma levels of gonadotropins found in HG were comparable with those found in SCO, while mean plasma testosterone levels in these patients were significantly lower than in SCO or NG. A significant decrease in the mean number of spermatids was present in HG, while the mean numbers of B spermatogonia (0.6 +/- 0.2) and preleptotene spermatocytes (0.6 +/- 0.1) were significantly elevated in comparison with NG (0.4 +/- 0.1 and 0.3 +/- 0.2, respectively). In all men with HG a GnRH test (100 micrograms i.v.) was performed and the relative increase of plasma FSH (maximum/basal level) correlated positively with the number of A-pale (r = 0.85, P less than 0.05) and B spermatogonia (r = 0.81, P less than 0.05). In NG group basal levels of FSH correlated with A-pale (r = 0.90, P less than 0.001) and B spermatogonia (r = 0.59). It seems that FSH plays a role to maintain the number and the differentiation rate of spermatogonia in men and is responsible for the hyperactivation of spermatogonia when secreted in excess. Hyperactivation of spermatogonia probably develops to compensate quantitative decrease in gamete production.(ABSTRACT TRUNCATED AT 250 WORDS)