✓ The injection of Pantopaque into the ventricles of normal and hydrocephalic dogs produced a variety of acute and chronic pathological changes. Multiple granulomatous lesions developed in the ventricular wall and the surrounding brain parenchyma, choroid plexus, cranial nerves, and arachnoid membrane. Adhesions formed in several areas of the ventricles, and Pantopaque became encysted in the third ventricle and tips of the temporal horns. In general there were more serious changes in the animals that had a greater degree of hydrocephalus. Relatively mild lesions were noted in normal animals.