Neural Tube Closure In Xenopus

The neural tube is the primordium that gives rise to brain and spinal cord in the central nervous system and thus its morphogenesis is thought to be one of the most important developmental events. In Xenopus laevis, it has been shown that there are at least two independent mechanisms to achieve the tube formation from a sheet of the neuroepithelial cells. One is a cell autonomous process apical constriction, the cell morphogenesis that minimizes the apical surface of the neuroepithelial cells at the hinge points and facilitates bending of the cell sheet. The other is the external force of nonneural ectoderm generated by the migration of the deep epithelial cell layer together with the superficial layer toward the midline that assists the closure movement. In this review, molecular and cellular mechanisms for neural tube morphogenesis are discussed.