Akihisa Shimoda

Morphological studies on cerebral cortical lesions induced by transient ischemia in Mongolian gerbil —Diffuse and peripheral pallor of the neuronal perikarya

SummaryUnilateral transient cerebral ischemia was produced in Mongolian gerbils by clipping the left common carotid artery for 1h. About 60% of the gerbils with neurological symptoms had post-ischemic seizures. The majority of those that had seizures died within a few days, and sections of their cerebral cortices contained many dark and shrunken neurons. However, the gerbils that did not have seizures survived without any severe complications. In the cerebral cortex of the latter, the neurons with diffuse or peripheral pallor of the perikarya were seen along with a small number of dark and shrunken neurons. Diffuse pallor occurred within a few hours following ischemia in layers III, V and VI, and disappeared 1 or 2 days after recirculation. Electron microscopically, these neurons showed dispersion of ribosomes, simple and elongated profiles of rough endoplasmic reticulum (r-ER), clustered vacuoles, and mild to moderate mitochondrial swelling. Occasional net-like tubulomembranous structures, probably derived from r-ER, were observed. On the other hand, peripheral pallor became apparent after 5 days following ischemia, usually involving layer II first and gradually extending to the deeper layers. Concomitantly, the amount of neuropil decreased and the dendrites exhibited tortuosity and irregularity in layer II. Electron microscopically, these neurons showed marked swelling of peripheral perikarya and polyribosomes and organelles were located peripherally to the nuclei. In addition, numerous degenerated axon terminals and distended dendrites were observed around the neurons. These observations indicate that diffuse pallor represents damage directly induced by ischemia and subsequent recirculation, while peripheral pallor is the delayed and remote effect of ischemia, probably due to degeneration of neuronal processes.

Congenital cerebellar neuroepithelial tumor with multiple divergent differentiations

SummaryA case of congenital cerebellar tumor is reported. The tumor is composed of a few incomplete tubular structures analogous to the neural tube, and of neuroblastic, mature ganglionic, astrocytic, ependymal and undetermined neuroepithelial cells. A tentative diagnosis of congenital cerebellar neuroepithelial tumor with multiple divergent differentiations is made: the histogenesis is discussed. From a histogenetic point of view this tumor is given the provisional name of matrix cell tumor.

PLASMA CELL GRANULOMA OF THE LUNG WITH EXTRAPULMONAL EXTENSION

A rare case of plasma cell granuloma of the lung in a 5‐year‐old girl showing extrapulmonal extension to the adjoining thoracic wall was reported. Intrapulmonal and thoracic wall granulomas revealed the same histopathologic features; proliferation of plasma cells and fibrous connective tissue. Although slightly atypical plasma cells were observed among many mature ones, immunohistochemical examination revealed polyclonal proliferation, confirming their inflammatory nature. Cellular components of fibrous connective tissue were identified as fibroblastic cells and myofibroblasts by electron microscopy. The present case and literature suggested the importance of the fact that “infiltrative” plasma cell granuloma had a tendency to occur in children. ACTA PATHOL. JPN. 35: 933–944, 1985.

Congenital Anaplastic Ependymoma: A Case Report of Familial Glioma

A congenital anaplastic infratentorial ependymoma, occurring in a female infant whose sister also died of brain tumor, is described. The tumor, located in the cerebellum and the fourth ventricle, is characterized by predominantly undifferentiated neuroepithelial cells associated with numerous mitoses, and partially of the cells demonstrating differentiation into ependymal cells and astrocytes. Of special interest is the fact that the elder sister of the patient had also died of a congenital glioma located in the cerebellum and the fourth ventricle, which leads to the discussion about the influences of genetic factors in the development of the familial gliomas as well as about the histogenesis of the tumor examined.

MINUTE CARCINOID TUMOR OF THE UTERINE CERVIX ASSOCIATED WITH MICROINVASIVE ADENOCARCINOMA, WITH REFERENCE TO ITS HISTOGENESIS

A rare case of carcinoid tumor of the uterine cervix associated with adenocarcinoma was reported. The carcinoid tumor was composed of round to polygonal cells showing solid or trabecular proliferation. Most of these cells and a small number of isolated cells wedged in neoplastic glands were positive with either Grimelius or Fontana‐Masson stains, and also positive for serotonin by immunostain (PAP method). Positively stained cells were thus considered to have the same histochemical nature as enterochromaffln cell. The carcinoid tumor was minute, about 2×2 mm and the adenocarcinoma was a microinvasive one. In some parts, smooth transition between both tumor components was observed. From these findings, it is suggested that both the carcinoid tumor and the adenocarcinoma in the present case were derived from a primitive precursor cell of common mesodermal origin. ACTA PATHOL. JPN. 37:1183–1198, 1987.

Effects of methylmercuric chloride of low concentration on the rat nervous system

In an earlier study the authors reported the effects of 20 ..mu..g/g of MeHg on the rat. After 2-week exposure to 20 ..mu..g/g MeHg, effects on behavior, pathological changes of brain and prolongation of EEP (early potential of evoked potential) latency were observed. So, in this experiment, they planned to expose rats to lower concentrations of MeHg. They therefore investigated the effects of MeHg exposure at a low concentration on behavioral indices, neurological signs, the circadian rhythm of behaviors, EEP, and pathology of the visual cortex and the sciatic nerve in rats.