Subependymal CSF Absorption in Hydrocephalic Edema — Ultrastructural Localization of Horseradish Peroxidase and Brain Tissue Damage

Summary

The absorption of cerebrospinal fluid (CSF) in hydrocephalic edema was studied in kaolin-induced experimental hydrocephalus in 30 rats by observing the ultrastructural localization of horseradish peroxidase (HRP) as a tracer in relation to neuronal and glial cell brain tissue damage. In the acute stage of hydrocephalus HRP reactive products were diffusely observed in various parts of the deeper brain than in the chronic stage; its reaction products were distributed diffusely in the extracellular spaces and blood vessel walls and some of them were observed in the glial cells and neurons through the routed CSF transport area in both the acute and chronic stage.

In the chronic stage of hydrocephalus, the edema fluid was localized around the ventricle and there were reactive astrocytes with increased glial filaments due to the effects of reactive change caused by intracytoplasmic edema in the glial cells and degenerative changes in some neuronal processes. In blood vessel walls, HRP reactive products were mostly localized in the basement membrane, the increased pinocytotic vesicles of endothelial cells, and in swollen astrocytes in contact with the blood vessels in the subependymal layer. According to these findings, it become clear that hydrocephalic edema in the chronic stage is rapidly absorbed in the limited subependymal layer because of facilitation of CSF absorption caused by increased permeability of the reactive cells of the vessels.