The effect of cytochalasin B on the neuroepithelial cells of the mouse embryo

Abstract

Abstract Eleven‐day mouse embryos were cultured in a medium containing cytochalasin B (10 μg/ml) to examine the effect of the drug on the developing CNS. The embryos were exposed to the drug for two hours. After culturing, the embryos were prepared for light and electron microscopy and the neuroepithelium of the cerebral vesicles was examined. The following abnormalities were noted in the cytochalasin B‐treated embryos: (1) mitotic figures were situated in the middle of the neuroepithelial layer instead of on the lumen, indicating that premitotic nuclear migration had been prevented; (2) binucleate cells were found in the neuroepithelial layer, indicating that cytochalasin B does not interfere with mitosis but prevents cytokinesis; (3) the microfilaments usually seen in the apex of the neuroepithelial cells were disrupted and formed an amorphous mass of filamentous material; (4) some neuroepithelial cells were free in the lumen, whereas others protruded into the ventricle but appeared to remain attached to the internal limiting border by their junctional complexes; and (5) in some regions the neuroepithelial cells had broken away from their end‐feet at the basal lamina. These morphological changes were associated with a change in the internal limiting boundary from concave to convex and vacuolation of the external processes of the cells. The relationship between cytochalasin B, microfilaments and these morphological changes is discussed.