Cellular basis of neuroepithelial bending during mouse spinal neural tube closure.
Bending of the neural plate at paired dorsolateral hinge points (DLHPs) is required for neural tube closure in the spinal region of the mouse embryo. As a step towards understanding the morphogenetic mechanism of DLHP development, we examined variations in neural plate cellular architecture and proliferation during closure. Neuroepithelial cells within the median hinge point (MHP) contain nuclei that are mainly basally located and undergo relatively slow proliferation, with a 7 h cell cycle length. In contrast, cells in the dorsolateral neuroepithelium, including the DLHP, exhibit nuclei distributed throughout the apico-basal axis and undergo rapid proliferation, with a 4 h cell cycle length. As the neural folds elevate, cell numbers increase to a greater extent in the dorsolateral neural plate that contacts the surface ectoderm, compared with the more ventromedial neural plate where cells contact paraxial mesoderm and notochord. This marked increase in dorsolateral cell number cannot be accounted for solely on the basis of enhanced cell proliferation in this region. We hypothesised that neuroepithelial cells may translocate in a ventral-to-dorsal direction as DLHP formation occurs, and this was confirmed by vital cell labelling in cultured embryos. The translocation of cells into the neural fold, together with its more rapid cell proliferation, leads to an increase in cell density dorsolaterally compared with the more ventromedial neural plate. These findings suggest a model in which DLHP formation may proceed through 'buckling' of the neuroepithelium at a dorso-ventral boundary marked by a change in cell-packing density.
['McShane|Suzanne G|SG|', 'Molè|Matteo A|MA|', 'Savery|Dawn|D|', 'Greene|Nicholas D E|ND|', 'Tam|Patrick P L|PP|', 'Copp|Andrew J|AJ|']
D000818:Animals D002465:Cell Movement D049109:Cell Proliferation D019938:Cyclin D1 D004622:Embryo, Mammalian D008648:Mesoderm D051379:Mice D008807:Mice, Inbred BALB C D009432:Neural Crest D054258:Neural Plate D054259:Neural Tube D046569:Neuroepithelial Cells D054261:Neurulation D009672:Notochord D013116:Spinal Cord
Mouse Neural tube closure Embryo Cell proliferation Neurulation