Some scanning electron microscopic observations of the ependymal surface of the ventricles of hydrocephalic Hy3 mice and a human infant.

Two hydrocephalic Hy 3 mice and an infant with hydrocephalus and the Arnold-Chiari malformation were examined with the scanning electron microscope. Both mice had advanced hydrocephalus but had normal appearances in the basal regions of the ventricles. However, as the ventricular walls were ascended first the cilia gradually disappeared, then the microvilli, and finally on the roof of the ventricle the ependymal cells disappeared leaving the subependymal layers exposed. The infant had mild hydrocephalus and normal ependymal appearances. The most likely explanation of these findings is that they are a consequence of raised intracranial pressure, and are not the cause of hydrocephalus.