Maturation of sperm and ovum are not autonomous processes. Rather, germ cell activity is controlled by a regulatory center in the hypothalamus. This assures germ cell maturation, fertilization, and development of the fetus until birth. Command, functional release, and feedback take place by humoral pa fhs which involve gonadotropin releasers, gonadotropins, and sex hormones. Even in antiquity, attempts at birth control involved a search for substances which might inhibit the essential physiological and biochemical reproductive processes. This report deals with more recent efforts along these lines.
I. Physiology of Reproductiondividual is heaIthy and in a satisfactory nutritional state [l]. In females, on the other hand, germ cells capable of fertilization are present only at periodic intervals. meir periodicity is reflected in the menstrual which can be considered as resulting from the failure of a mature OVUm to have become fertilized.[I] C. Lutwak-Mann, Vitamins and Hormones 1 6 ,~ (1958).Successful conception requires the presence of male germ cells capable of fertilization and of female cells that can be fertilized. These cells are present at certain ages only. From puberty on, their presence at all times can be demonstrated only in males, provided the in-
531Constant maturation of the semen and periodic maturation of ova do not take place autonomously, i.e. independently of what occurs in the rest of the organism. Rather, the activity of the organs giving rise to the germ cells, i.e. of the gonads (testes and ovaries), is subject to central control and exerts feedback effects on all other central controls. The hypophysis-hypothalamus constitutes the regulatory center of both males and females. The hypophysis with its anterior lobe is located on or within the base of the cranium. Its commands are issued in response to orders that originate in the diencephalon (hypothalamus), located directly above the hypophysis. The sexual nerve center is located there. Throughout the entire reproductive system, the preferred path for the transmission of commands, release or initiation of functions, as well as feedback, is humoral in nature.In all likelihood, functional release of pituitary activity occurs by way of short-chain peptides, the gonadotropin releasers. The substances released in time by the pituitary are water-soluble protein hormones of as yet unknown structure, i. e. the gonadotropins. The structure of the substances released by the gonads in response to the gonadotropins is known: both male and female sex hormones are steroids. The latter can be classified in terms of Clg-steroids (estrone derivatives, or estrogens), Clg-steroids (androstane derivatives, or androgens) and Czl-steroids (pregnane derivatives, or gestagens). On the one hand, these sex hormones feed back information on started secretions in the neuroendocrine system; on the other hand, they induce the necessary preparation of the germ-cell transporting and protecting portions of the genital system. In other words, they cause the secretions of t...
