Human spermatogenesis in vitro: Respective effects of follicle-stimulatinghormone and testosterone on meiosis, spermiogenesis, and sertoli cell apoptosis

In spite of the availability of abundant data about in vitro spermatogenesi s in laboratory animals, studies on human in vitro spermatogenesis are scar ce. This study employed a relatively simple culture system, involving all c ell types of seminiferous tubules, to analyze the effects of FSH and testos terone (T) on different characteristics of human germ and Sertoli cells in culture. By using fluorescence in-situ hybridization, we show that in vitro reduction of germ cell ploidy can be stimulated by FSH but not by T. FSH, but not T, also induced unexpectedly rapid (24-48 h) morphological changes resembling spermiogenesis, although individual changes (spermatid nucleus c ondensation and protrusion, cell body elongation, and flagellar growth) pro ceeded in an uncoordinated way and mostly resulted in the development of ab normal forms of elongated spermatids. Though ineffective alone, T potentiat ed the effects of FSH on meiosis and spermiogenesis. These effects of T wer e probably caused by the prevention of Sertoli cell apoptosis, an effect th at could not be mimicked by FSH. These data show that, in the presence of h igh concentrations of FSK and T, human spermatogenesis can proceed in vitro with an unusual speed, but the resulting gametes are morphologically abnor mal. The potential practical relevance of these findings to assisted reprod uction remains to be assessed.