With the advent of transgenic technology, which allows the identification of specific gene activities in developing mammalian organisms, the house mouse has once again taken a very important place in experimental research as one of the genetically best understood mammals. More than ever, molecular biologists are in need of a detailed, standardized description of the anatomy of the developing mouse embryo. In this classic compendium, now brought up to date and corrected, the author presents each stage of mouse development in photographs and micrographs using hybrids of two inbred strains as a standard. Organ systems are systematically reconstructed from fertilization until after birth. Molecular biologists tracing the effects of genetic manipulations, as well as students and researchers of developmental biology, will appreciate the renewed availability of this standard reference work for its unparalleled accuracy, its attention to anatomical detail, and the extent of its documentation.