ABSTRACT
Morphological changes in the ependymal lining of the hydrocephalic brain included stretching and tearing of the ependyma, thickening and gliosis of the subependymal layer, progressive loss of cilia and microvilli from the ependymal surface, and widening of the extracellular space. In the CT scan of the brain, periventricular low density was one of the common findings in hydrocephalus. The present experiment was performed to investigate not only the ultrastructural changes of the ventricular walls in hydrocephalus but also the morphological basis of periventricular lucency detected in the brain CT scan of the hydrocephalic patients. Hydrocephalus was induced in rats by intracisternal injection of thick kaolin suspension after surgical exposure of atlanto-occipital membrane. Lateral wall of the lateral ventricle was examined with transmission electron microscope in 3 different groups(6 rats at 1 week after the hydrocephalus, 8 at 2 weeks, and 4 at 8 weeks). The results were as follows: 1) Ultrastructural changes of the ependymal lining in hydrocephalic rat were flattening of ependymal cell and its nucleus, loss of cilia and microvilli from the ependymal surface, widening of the junctional complex, vacuoles and enlargement of cisternal space of rough endoplasmic reticulum in cytoplasm, and thicking and gliosis of subependymal layer. 2) These changes became more severe with longer duration of hydrocephalus. 3) Widening of junctional complex was considered to be the morphological basis for migration of ventricular cerebrospinal fluid into the periventricular white matter with resultant periventricular low density in the CT scan of the brain.