So far, the clearest picture of living embryos comes from zebrafish and fruit flies. Ten years ago, Philipp Keller, a physicist and biologist at the Jenice Research Institute in the Howard Hughes Medical Institute, and his colleagues developed the first “digital embryo” of zebrafish, in which the zebrafish was a transparent striped fish that is usually provided to scientists for research. They scanned the zebrafish embryos with a light sheet…