TOPICS: Germ layer origins, surface ectoderm, neuroectoderm, neural tube, neural crest cells, neurulation, notochord, neural plate, nucleus pulposus, ectoderm, neural fold, neural groove, epiderm, neural tube progression, brain segments, cavities and walls derived from the neural tube, prosencephalon (forebrain), mesencephalon (midbrain), rhombencephalon (hindbrain), spinal cord, telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon, lateral ventricles, aqueduct, 3rd ventricles, 4th ventricle, cerebral hemispheres, thalamus, hypothalamus, midbrain, cerebellum pons, medulla oblongata, neurospore, fusion failure, amniotic cavity, neural tube defect, spina bifida occulta, meningocele, myelomeningocele, myeloschisis, caudal neural tube defects, cranial neural tube defects, anencephaly, folic acid, valproate, carbamazepine, holoprosencephaly, sonic hedgehog (SHH), midline facial defects, spectrum of midline defects and holoprosencephaly, lissencephaly, agyria, neuronal migration, gyri, sulci, microcephaly, ventriculomegaly