This Fast-Track SBIR contract will develop a high throughput assay to test compounds for toxic effects on Neural Crest cells. The Neural Crest forms, transiently, within the embryo; the Neural Crest cells then migrate to different sites and develop into various tissue types, including peripheral neurons, glial and smooth muscle, and bone. Thus, compounds that inhibit Neural Crest cells migration or have other toxic effects, will have profound effects on embryonic development. We have developed a Neural Crest Cell Migration assay Neural Crest cells, utilizing cells derived from human embryonic stem cells. The cells are seeded in multi-well plates, allowed to reach confluence, then scratched to form a cell-free region; test compounds are then added and the number of cells that migrate into the area are quantified via automated digital microscopy.