Figure 3: Schematic representation of the formation of the mouse spinal neural tube. Process of closure of the PNP of embryos undergoing Mode 1 (a, b, d) or Mode 2 (a, c, d) neurulation. (a) Neuroepithelium thickens and converges; (b) formation of bilateral neural folds which are elevated (Mode 1); (c) apposing tips of neural folds aided by bending at the dorsolateral hinge points (DLHP) of the bilateral neural folds (Mode 2); (d) adhesion and fusion at the tips of the neural folds; (e) remodeling of the neural tube. Ne, neuroepithelium; Se, surface ectoderm; Me, mesoderm; MHP, median hinge point; DLHP, dorsolateral hinge points; POAF, point of adhesion and fusion; Nt, notochord.