Cell proliferation of the neuroepithelium in embryonic stages of induced spina bifida.

The generation cycle of day 10 1/4 rat embryo neuroepithelium was determined radioautographically and compared with prospective spina bifida aperta embryos of the same age. This early stage of presumptive myeloschisis was induced with trypan blue. No differences in the duration of the whole cell cycle and its different stages were found. The experiments reported here suggest that trypan blue treatment does not alter the proliferation kinetics of the neuroepithelial cells. This strengthens the hypothesis that the spina bifida aperta resulting from trypan blue treatment is primarily due to an abnormality in the unsegmented mesoderm underneath the neural wall.