Fig. 1. Apical constriction and apicobasal cell elongation in the neural epithelium during neural tube closure. (A) Projection of confocal optical transverse sections through the anterior neural plate of neurulating Xenopus embryo. (a') High-magnification view of a neural epithelial cell from A. (B) A schematic diagram of the section in A, illustrating the neural epithelial cells (red) and other surrounding tissues (grey). (b') A schematic diagram of the section in a'. Cells in hingepoint regions constrict and elongate (arrow), cells in intermediate regions elongate, but constrict only a little (arrowhead). (C) Graph illustrating changes in apical constriction (blue; ratio of apical surface to basal surface measured from cross-sections) and apicobasal cell elongation (red; cell height in µm) of neuroepithelial cells during neural tube closure (stages 14-19; n=10 cells per stage). (D) Schematic illustrating the change in neural epithelial cell shape during neural tube closure.