Essentials of Mouse Development

Abstract

Many scientists interested in epigenetics, especially those coming from a background of microbial or plant genetics, may not be sufficiently familiar with the features and nomenclature of mouse development to easily understand the chapters in this book devoted to mammalian epigenetic phenomena. The purpose of this chapter is to provide in a few pages the essentials of mouse development, with emphasis on the features that seem to be of importance for epigenetics. As a review and practical introduction to mouse embryology, a book entitled Manipulating the Mouse Embryo (Hogan et al. 1994) is highly recommended. Most epigenetic phenomena in mammals, including cell determination, X-chromosome inactivation, and imprinting, are established in the early embryo and then maintained in somatic cells of the adult. Cell determination and differentiation during mammalian development is also highly dependent on cell memory. In general, the response of a mammalian cell to a signal depends on developmental history. Events that occurred many cell generations earlier are remembered, presumably by somatically heritable epigenetic mechanisms.

FERTILIZATION AND PREIMPLANTATION DEVELOPMENT
Fertilization takes place in the oviduct approximately 1 hour post coitus (p.c.) (see Fig. 1). Development of the resulting zygote is slow until implantation, which does not take place until about 4.5 days p.c. Full maturation of the egg, including completion of the second meiotic division and extrusion of the second polar body, normally takes place after fertilization and is not complete until 2–5 hours p.c. During egg maturation and for some time thereafter, the male and female nuclei...