Obstruction of cerebrospinal fluid pathways produces changes in the parenchyma of the brain and spinal cord. A murine model of hydrocephalus (hy-3) used to study changes in the central canal of the spinal cord and these changes are correlated with events occurring in the intracranial compartment. The central canal is enlarged and subependymal interstitial edema is produced by cerebrospinal fluid at the same time as the intracranial ventricular system is expanding. Plugging of the obex results in collapse of the central canal. Ferritin tracer studies demonstrate transependymal flow of cerebrospinal fluid throughout the central canal.