Since in a previous study hypoxia and subsequent hypotension were considered to be essential for the pathogenesis of carbon monoxide encephalopathy (CO-encephalopathy), experiments were conducted to see whether a combination of nitrogen hypoxia and subsequent systemic hypotension of similar degree and duration as in the previous experimental CO poisoning could induce the same lesion in the CNS of cats. The partial pressure of blood oxygen was reduced to less then 26 mm Hg by increasing the concentration of nitrogen in N2/O2 gas to be inhaled in 1.5h and then the aortic blood pressure (BP) was reduced to 60-80 mm Hg by blood depletion and ganglion-blockage for 1h. In 11 of the 15 cats, lesions were produced in the CNS which were similar by light and electron microscopy to those in CO-encephalopathy. In control groups which were treated by hypoxemia only, hypotension only or a combination CO2-gas inhalation and hypotension without hypoxemia, such lesions were not found in the cerebral white matter. Considering the pathogenesis of lesions in the cerebral white matter in both nitrogen hypoxia and CO-poisoning, two factors i.e., hypoxemia and subsequent systemic hypotension, are common and essential. Further, the enormous vasodilatation in the cerebral white matter induced by hypoxemia and subsequent drop in BP seem to cause a more severe circulatory disturbance in the cerebral white matter than in the cortex.

An autopsy case of a 69-year-old female with pineocytoma was reported.The tumor showed neuronal differentiations, which were confirmed not only by light microscopy and electron microscopy, but also by a cell marker of neuronspecific enolase. In addition, existence of astrocytes in the tumor which distributed sparsely was ascertained by electron microscopy and cell markers such as S-100 protein and glial fibrillary acidic protein. ACTA PATIIOL. JPN. 34 : 911 -918, 1984. IntroductionPineal tumors originating from the pineal parenchymal cell are classified into medulloblastoma-like pineoblastoma and pineocytoma which resembles the normal pineal tissue.7.20 The former is often accompanied by retinoblastomatous differentia-tion7-20p24 and the latter sometimes assumes a form transitional to the former or shows differentiation to ganglion cells and/or ~~t r~~y t e~.~~~.~~~ Such neuronal or glia: differentiation of true pinealoma is a morphological concept, and biochemical substitution is yet to be completed. Recently, several cell markers were developed such as S-100 protein for astrocytes or Schwann cells, glial fibrillary acidic protein (GFAP) for astrocytic processes, and neuron-specific enolase for neurons and paraneurons. We conducted an autopsy of a patient with pineocytoma using such markers in addition to traditional histology and electron microscopy; and, based on these findings, discussed the origin of pineocytoma. hldical trnd Dent,sl tIniversit,y, No. 5-45, 1-chome, Yushima, Bunkyo-ku, Tokyo, .JAPAN. 912 PINEOCYTOMA Actu Pathol. Jpn. Case ReportThe patient was a 69-year-old female. Her clinical onset was with gait disturbance one and a half years before her death. Five months later she became unable to walk and developed urinary incontinence and dementia. A pineal tumor was disclosed on CT, and because of her advanced age a ventriculo-peritonea1 shunt operation instead of tumor extirpation was performed and irradiation of 5,000 rads to the tumor was administered. Her gait disturbance and dementia were alleviated by the therapy, but eight months postoperatively urinary incontinence recurred and three months later she was readmitted to our hospital because of her disability in walking and dementia. The recurred pineal tumor was found on CT to be of similar size to the initial mass but the V-P shunt was still patent. On the twelfth hospital day, nonketotic hyperosmotic diabetic coma developed and she expired on the 20th hospital day.Autopsy revealed a pigeon-egg sized, well-demarcated tumor in the pineal region, compressing the bilateral posterior walls of the third ventricle without adhesion or invasion (Fig. la). There was neither intracranial dissemination nor extracranial metastasis. Other viscera presented non-remarkable changes except for several foci of bronchopneumonia in the bilateral lungs. MethodsFor lighbmicroscopy, the pineal tumor was fixed in 4% buffered-formaldehyde and stained with the followings : hematoxylin-eosin (H.E.), periodic acid-Schiff with and without diastase-digestion, phosphotungs...