Neuroepithelial and ependymal changes in HTX rats with congenital hydrocephalus: an ultrastructural and immunohistochemical study.

To investigate the pathogenesis of congenital hydrocephalus the brains of HTX rats aged between 16 days and 4 weeks and the brains of normal Wistar rats of the same ages were examined. In the fetal HTX rat brains, the lateral ventricles were symmetrically dilated from 20 days of gestation. The neuroepithelium bordering the ventricles showed thinning with cellular disarrangement and deformity. Similar neuroepithelial abnormalities were also found in the lateral ventricles of the HTX rat brain with no macroscopic signs of hydrocephalus at 20 days of gestation. The neuroepithelium showed flattening of the cells, widening of the intercellular spaces, formation of microvilli on the detached lateral cell surfaces, and frequent macrophage infiltration. On the other hand, the neuroepithelial cells of the third ventricle and the aqueduct were affected less severely or showed no significant abnormalities. Immunohistochemically, most of the neuroepithelium and ependyma of the lateral ventricles were positive for vimentin in both prenatal and postnatal hydrocephalic HTX rats, while a small number or none of those in normal control rats were positive. These morphological changes suggested that preferential involvement of the lateral ventricular neuroepithelium might be closely associated with the pathogenesis of congenital hydrocephalus in HTX rats.