Comparative reproductive physiology of nonmammalian species

This chapter aims to emphasise the ways in which reproductive physiology in fish, amphibians, reptiles and birds differs from that in mammals. Although reproductive physiology has shown considerable adaptation through evolution, many aspects, including the biosynthesis and structure of steroid hormones, and to some extent their functions, have shown a remarkable degree of conservation. Recent concern about endocrine disruption has focused on natural or synthetic chemicals interacting with gonadal steroid receptors to agonise or antagonise the actions of the natural ligands. Gonadal steroids are involved in most aspects of reproduction, from sexual differentiation during embryonic development to gamete maturation and sexual behaviour, in all vertebrates. Physiologically significant endocrine disruption has the potential to compromise: reproduction in many ways.