Light and electron microscopic studies of experimental hydrocephalus

Summary

A light and electron microscopic study of the ependymal and subependymal regions of experimental hdrocephalic cats was made. Hydrocephalus was induced by injection of kaolin into the cisterna magna. Cerebrospinal fluid (CSF) turnover was measured in all experimental cats by ventricular perfusion just prior to glutaraldehyde fixation. The cats were sacrificed at 7 (acute hydrocephalus) and at 21 or more days (chronic hydrocephalus) after kaolin. The major pathological findings were: flattened and outstretched ependymal lining, detachment of ependymal cells and rarefaction of subependymal areas with increase in the extracellular space. The significant morphological alterations in acute hydrocephalus, characterized by a marked decreased rate of CSF absorption, were flattening and outstretching of ependymal cells with minimal rarefaction of subjacent tissues. In the acute animal with a measurable amount of CSF absorption, and more clearly, in the chronic animal with higher rates of CSF absorption, detachment of ependymal calls, significant rarefaction of subependymal tissues, and marked increased subependymal extracellular space were the predominant changes. It is concluded that these pathological changes provide the morphologic substrate for transventricular absorption of CSF.