Inhibin : with an old concept towards a new approach in reproductive physiology
Fertility in mammals ~as recei~ed considerable attention as far back as written reports exist. In the last centennium, the study of fertility has surpassed the level of merely descriptive and empirical science and has been applied to solve some problems of the regulation of fertility. This has contributed to the treatment of fertility disorders arid to birth control in man, as well as to improvement of animal husbandry. Our knowledge of the processes controlling fertility has increased due to clinical observations and the use of experimental techniques ranging from para- biosis experiments, castration and hypophysectomy to brain l~sions and 'implantations of materials such as tissue fragments. Information has been obtained about the interplay between central nervous structures, pituitary gland and the gonads, and about the role of hormones secreted by these organs. In the most simple scheme, these interactions firstly involve the control and release of hypothalamic releasing factors, which reach the anterior pituitary gland by way of the portal vessels. In turn, the pituitary gland releases in both male and female animals gonadotrophic hormones: follicle stimulating hormone (FSH) and luteinizing hormone (LH). These hormones enter the circulation and reach their end-organs, testes or ovaries, in which they influence both morphology and function. The testes and ovaries, apart from producing gametes, respond with the production of gonadal hormones, which do not only control the secretion of hypothalamic releasing factors and the pituitary secretion of FSR and LH, but also influence the development and maintainance of acces_sory sex organs, secondary sex characteristics and sexual behaviour. One of the problems in testicular and ovarian (patho)physiology is the nature and action of these gonadal hormones.