In this, our Second Edition of Reproduction in Mammals, we are responding to numerous requests for a more up-to-date and rather more detailed treatment of the subject. The First Edition was accorded an excellent reception, but the first five books were written ten years ago and inevitably there have been advances on many fronts since then. As before, the manner of presentation is intended to make the subject matter interesting to read and readily comprehensible to undergraduates in the biological sciences, and yet with sufficient depth to provide a valued source of information to graduates engaged in both teaching and research. Our authors have been selected from among the best known in their respective fields. This volume discusses the manifold ways in which hormones control the reproductive processes in male and female mammals. The hypothalamus regulates both the anterior and posterior pituitary glands, whilst the pineal can exert a modulating influence on the hypothalamus. The pituitary gonadotrophins regulate the endocrine and gametogenic activities of the gonads, and there are important local feedback effects of hormones within the gonads themselves. Non-pregnant females display many different types of oestrous or menstrual cycles, and there are likewise great species differences in the endocrinology of pregnancy. But the hallmark of mammals is lactation, and this also exerts a major control on subsequent reproductive activity.