First Stages of Embryonic Development, Histogenesis of the Placenta, and Pregnancy Maintenance

In this chapter, the early embryological events are considered, together with genetical and endocrinological influences. The histogenesis of the multiplex placenta is described, as related to sheep and cow, as a gradual, slow, and fragile process, in the frame of the most relevant information on genetical molecular enhancers and moderators. The function of the corpus luteumCorpus luteum (CL) and some steroids, together with nutritional and immunological aspects of embryonic survival, is presented. Most processes are illustrated.