Neural tube closure defects following in vitro exposure of mouse embryos to xylocaine.

Early somite mouse embryos were exposed in vitro to xylocaine (Lignocaine hydrochloride) to examine its effect on neural tube closure. When embryos were exposed to 2.4 x 10(-4) mg/ml xylocaine for the entire 36-hour culture period, cephalic neural tube closure did not take place. Then examined by SEM, the neuroepithelial cells of these embryos were incompletely elevated, and depressions in their lateral surfaces were often observed. TEM observations on the neuroepithelium of similar embryos indicated that the microtubules and apical microfilament bundles were absent. The role of calcium in the maintenance of neuroepithelial cell asymmetry and in the production of these defects is considered.