Hormonal Regulation of Male Reproduction (with Reference to Infertility in Man)

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Abstract
In mammals, pituitary control of spermatogenesis varies with age. In the rat, before puberty FSH is highly active whereas LH is not; after puberty it seems that LH alone is able to support spermatogenesis. The mode of action of hormones is discussed. In the human, in case of infertility due to hypogonadotrophic hypogonadism, spermatogenesis can be restored by HCG or HMG. The best results are obtained after simultaneous treatment with both hormones, LH activity being predominant.A review of the hormonal regulation of spermatogenesis in experimental animals and in man is presented. In the rat, the roles of follicle stimulating hormone (FSH) and luteinizing hormone (LH) vary with the age of the animal. FSH is effective in the prepubertal rat in the support of spermatogonial multiplication. LH is active in the hypophysectomized adult. FSH acts by binding specifically to receptor sites on cellular membranes of the seminiferous epithelium inducing biochemical changes. The development of a system which limits the response to FSH according to age is suggested. Information on the action of LH is less understood. In the human, information on spermatogenesis comes from treating disorders. In treating infertility, gonadotropins are used from human origin: 1) human pituitary extracts (HPG); 2) human chorionic gonadotropin (HCG); and 3) human menopausal gonadotropin (HMG). In the prepubertal testis, spermatogenic activity can be initiated with HCG or HMG. Spermatogenesis proceeds only to primary spermatocytes. Morphological maturation of Sertoli cells occurs as long as LH-like activity exceeded FSH-like activity. In hypogonadotropic hypogonadism, FSH has been shown to be inactive on germ cells while LH allows resumption of meiosis after hypophysectomy. HMG or HCG given simultaneously often provoke a noticeable stimulation of spermatogenesis which progresses to the release of some sperm. Further research is needed to elucidate the relationship between different testicular compartments in the production of sperm.