Surface defects in ventricular cells of brains of mouse embryos homozygous for the Loop-tail gene: scanning electron microscopic study.

Luminal surfaces in the mesencephalon and rhombencephalon in normal mouse embryos and those homozygous for Lopp-tail were studied by means of scanning electron microscopy. Ventricular cells in the ventrolateral regions of normal day-10 and -11 brains showed single apical cilia and microvilli, whereas those in ventromedial regions showed a dense network of microvilli and bulbous projections which tended to obscure the apical cilia and cellular outlines. Similar regional differences occurred in the Loop-tail brains, although there was a marked decrease in the number and density of microvilli and bulbous projections. At days 12-14 of gestation the latter brains also showed a flattening of cell surfaces, shallow depressions, and craterlike ruptures in the plasma membranes.