Figure 1. Neural crest development and axial levels of origin.

(a) Neural crest cells are induced during gastrulation in the neural plate border between the neural plate and the nonneural ectoderm. During neurulation, the neural crest becomes specified and the neural folds reposition the neural crest to the dorsal midline. Following neural tube closure, premigratory neural crest cells undergo an epithelial-to-mesenchymal transition and delaminate from the neural tube to migrate throughout the embryo. (b) Neural crest cells arise from nearly all axial levels in the vertebrate embryo, and are categorized into four broad groups (cranial, vagal, trunk, and sacral) based on their level of origin along the anterior-posterior axis.