Abstract: In order to study the lesions and pathogenesis of braindsath. the experimcnts were performed in 33 cats to causerersistent intracranial hypertension by extradural inflatingballon. The animals were divided into 7 groups accordingto the duration maintained on the respirator. The resultsshow: (1) Dilated and fixed pupils. cessation of respiration and flattening of EEG, (2) A varying degree of cerebral herniations, especially the herniation of foramenmagnum and dissemination of the herniated fragments ofcarebellar tonsillar tissue into the spinal subarachnoidspace (3) The longer of the duration maintained on respirator. the more severe of the neuronal necrosis andautolysis which occured in whole brain at 9-12 hours.

Key words: Brain death, Intracranial hypertension, Carebral herniation, Neuronal necrcsis and autolysis