Ultrastructural White Matter Changes in Acute Experimental Hydrocephalus in the Rhesus Monkey

Recently Milhorat developed a surgical technique for producing obstructive hydrocephalus in the rhesus monkey. With this technique, pronounced ventricular enlargement occurred within a few hours following obstruction of the 4th ventricle. Employing this method, the authors have been studying brain sections from hydrocephalic monkeys by light microscopy. Of interest is the finding that, within 48 hours following obstruction of the ventricular system, large areas in the periventricular white matter appeared pale in myelin stains (Fig. 1). These regions were lateral to the temporal and occipital horns of the lateral ventricles. Using various lipid stains, no demyelinization could be detected in these areas. It was, therefore, decided to investigate this finding by electron microscopy in order to determine whether or not there were detectable ultrastructural changes in the white matter.