[Mitotic activity and rosette formation in the neuroepithelium of the embryonic human neocortex in vitro]

Fragments of anterior cerebral vesicle wall were exposed in 6-8 weeks human embryos and cultured for up to 48 hrs in media 199. Two types of neuroepithelial cells dynamics were demonstrated: the first one is associated with invaginative movements of the layer (apical contractions and elongation of neuroepithelial cell processes are seen, the other one-with cell mitotic division (apical processes become shorter and wider and nuclei reach germinal zone). Prevalent cell dynamics type is determined by media composition. Type I predominates in serum-free media, while type II-in media containing embryonal serum. The lack of correlation between the extent of neuroepithelial layer bending and number of mitotically dividing cells in it indicates invagination process independence from cell divisions. Thus, neuroepithelial layer invagination is not stimulated by mitotic activity and does not stimulate it.