TOPICS: Endoderm (internal layer) mesoderm (middle layer), ectoderm (external layer), mesodermal defects, VACTERL associations, association, surface ectoderm, anterior pituitary (Rathke pouch), neural tube, neuroectoderm, neural tube defects, folic acid, neurulation, neural crest, melanocytes, enterochromaffin cells, odontoblasts, leptomeninges, notochord, neural plate, neural groove, epidermis, central nervous system, PNS ganglia, endocardial cushions, atresia, TE fistula, tracheal lining