[Fertility control--evolution of hormones and regulatory mechanisms--endocrinology of the prostate]

Natural methods of fertility control are exemplified with studies on wild animals. A study on wild goats shows the effect of hours of daylight on gonadal function. Longer daylight period depresses gonadotropin and testosterone secretion and decreases testicle size. The regulatory mechanism is a light-impulse stimulating the pineal body via nervous system pathways. A study on breastfeeding shows this as a regulatory mechanism in ovulation. Intensity of breastfeeding correlates with the length of anovulation as shown in primitive cultures chimpanzees and gorillas. The current status of steriod hormone contraception is reviewed with both beneficial and adverse effects. Although estrogen and gestagen content of current contraceptives is lower their effects remain basically unchanged. They are not recommended for women over 40 years who smoke. LH-RH antagonists (e.g. Buserelin) are still under study for their effect on ovulation. Used as a nasal spray Buserelin depresses gonadotropin secretion. Adverse effects are menstrual irregularity and endometrial proliferation. Exogenously administered PGE2 and PGF2alpha induce menstruation and/or abortion by their action on uterine contraction and cervix dilatation. Animal experiments with luteolytic agents and antigestagens do not translate very well to humans and primates. Research on this continues. Practical problems remain in birth control; there is no ideal contraceptive method. Sterilization remains the most successful method of fertility control. There is need for more education on reproduction physiology and contraception for lay people and professionals. Other papers in this symposium discuss the comparative evolution of endocrine physiology of invertebrates lower vertebrates and mammals. Further papers discuss the endocrinology of the normal prostate and prostatic diseases.