The investigator has developed a novel approach involving the injection of carbocyanine dyes (diI, di0, diA) into developing chick dermomyotomes to determine the origin and migration of cells giving rise to the myotome. Experiments will be performed to locate potential centers of mitotic activity, precisely locate origin of myogenic precursor cells and their paths of migration, determine origin of precursors of hypaxial myogenic cells, and examine precursor-product relationships.