Proceeding from a single cell to a complex organism requires the intricate orchestration of a number of biochemical processes. If any thing goes wrong the result is a defective fetus. One of the most difficult of these processes to study is cell motion. Now biologists at Vanderbilt and the University of Missouri have taken a major step towards understanding the mysterious molecular processes that direct cells to the correct locations within a developing embryo: understanding that the researchers hope will eventually provide treatments for babies with birth defects such as spina bifida. They have done so by studying the zebrafish, a small fish from the Ganges River in India that has become an important animal model for the study of development in vertebrates, animals with backbones