The architecture of an embryo results from complex molecular interactions in time and space. The secrets of these processes are yielding quickly to genetic and cellular dissection in flies, mice, and other species, and finding application to human embryology. This remarkable volume presents the most current and authoritative survey of the induction of axes, control of cell migration, and the development of nervous system, limbs, wings, and other organs, seen through the perspective of sixty-one renowned investigators. Completed by a summary that charts the future of this dynamic field, this is a volume no laboratory interested in genes and development can afford to be without.