Yukio Tagashira

Acute Cerebral Infarction and Hypotension: An Ultrastructural Study

A comparison was made of morphological changes in brain tissue following periods of hypotension plus ischemia (due to occlusion of the middle cerebral artery) with those changes resulting from ischemia alone. It was found that a greater degree of swelling was present in the brains of those animals subjected to hypotension and ischemia than in those with vascular occlusion only. The type of organellular response in the hypotensive/ischemic animals was one of vacuolar formation within mitochondrial, endoplasmic reticular, and Golgi elements. It is concluded that the compound effects of hypotension plus ischemia result in more widespread and complex morphological response than either hypotension or ischemia alone. These morphological findings offer supportive data which will be further correlated with a future report on comparable changes in cerebral metabolism and hemodynamics.

Acute Ultrastructural Changes in the Middle Cerebral Artery Due to the Injury and Ischemia of Surgical Clamping

Ultrastructural changes in the zone of clamping of the middle cerebral artery of the squirrel monkey are described after application of a surgical clip. The experimental model utilized has been widely applied to the study of cerebral ischemia and possibly has relevance to clamps applied to the cerebral vessels during neurosurgical treatment of patients with cerebrovascular disorders. The earliest changes within the arterial wall were found in the smooth muscle (media) and accompanying fasciculi of nerves. Changes within the nerve bundles were sufficiently advances following 4 hours of vascular clipping to suggest temporary or permanent impairment of neurogenic innervation of the cerebral vessels distal to the trunk of the vessel clipped.

The effects of glycerol on cerebral ultrastructure following experimentally induced cerebral ischemia

Ultrastructural changes in cerebral tissue subjected to temporary occlusion on the right middle cerebral artery for intervals of 30 min, 1, 2, 3, and 4 hr were studied after daily injections of 10% glycerol in saline. These changes were compared with previously reported data from untreated animals. The extent of tissue involvement was appreciably less in the glycerol-treated group as evidenced by the reduction of intracellular edema and fewer changes in the membranes of ultrastructural elements (mitochondria, endoplasmic reticulum, Golgi complex, and plasmalemma) known to be essential for cellular metabolism and function in the central nervous system.

Morphological responses of cerebral tissues to temporary ischemia.

The ultrastructural responses of cerebral tissue following temporary periods (1/2, 1,2,3, or 4 hour) of right, middle cerebral artery, (MCA) occlusion were studied acutely after a 3 day or 7 day interval following the removal of the MCA clip. Cortical and basal ganglia tissues for each ischemic duration were compared at 3 post-occlusive periods (acute, 3 days, 7 days). With the short periods of ischemic insult (1/2, 1, 2, 3, and 4 hour), the temporal and insular cortex contained no greater changes in the 7 day group than in the 3 day group. The basal ganglia were more susceptible to MCA occlusion as indicated by more marked cytological changes and/or necrosis in all intervals of ischemia.

Acute pericytic response to cerebral ischemia

Abstract It has been suggested that the pericyte, through its close relationship to the capillary unit, is involved in several functional roles. In some pathological states the cell has been reported to transform into a phagocytic form and become mobile. The role of pericytic involvement in the ischemic brain has not been previously reported. In this study of effects of temporary occlusion of the middle cerebral artery in the baboon, the pericytes were found to contain abundant “lysosomal-like” material in the shorter vascular occlusive periods whereas in the animals with longer ischemia, extensive intrapericytic edema was observed within the brain parenchyma. Pericytic susceptibility to edema was found to be less than that of the astrocytes. No pericytes were observed penetrating the surrounding basement membrane or transforming into structures suggestive of phagocytes. The pathological pericytic changes were quite independent of those appearing in the endothelial cells.

Morphological studies of the ventricular wall in cerebral infarction.

Abstract The morphological changes in the ependymal lining of the lateral ventricle at the level of the caudate nucleus were studied following periods of ischemia. Ischemia was produced by transorbital occlusion of the middle cerebral artery for periods of one-half, one, two, three, or four hours, respectively. Six animals were studied from each period of occlusion. Two animals per occlusive period were perfused with 3% glutaraldehyde for electron microscopy immediately after the removal of the clip, two were perfused at the end of a three-day period, and two additional animals were perfused one week after occlusion. Changes in the ependymal and subependymal layer were found as early as two hours after occlusion. These changes and those seen in the other groups consisted of intracellular vacuolization of the ependymal layer and edematous involvement within the subependymal (astrocytic) layer. The supraependymal (neural) structures appeared less susceptible to ischemia than the ependymal and subependymal layers.

The ultrastructure of the middle cerebral artery and its associated nerve fibers in the squirrel monkey and baboon

This study describes the ultrastructural characteristics of the middle cerebral artery and its related neural elements in the squirrel monkey and baboon. The cytoarchitecture of the M-1 segment as well as that of the smaller extracerebral and intracerebral vessels is comparable in both animals. Smooth muscle elements are occasionally found within the intimal lining. The nerve bundles associated with vessels contain fewer myelinated fibers as the vessel diameter decreases. The cytological relationship between the neural structures and the smooth muscle cells are discussed.