[Organization and regulation of spermatogenesis]

We briefly overview the process as well as hormonal and paracrine regulation of spermatogenesis. Initiation of sperm production occurs under stimulation by FSH and LH. Spermatogenesis can be maintained by testosterone alone at least qualitatively. Stimulatory function of gonadotropic hormones can be modified or modulated on the basis of the local environment present in the testis. Sertoli cells create the blood-testis barrier modulating the entry of substances into the seminiferous tubules. Sertoli cells play the main role in paracrine regulation of spermatogenesis by providing factors required for the development of germ cells. Substances regulating spermatogenesis as paracrine factors in the testis are summarized.