Vascular changes underlying cerebral lesions in stroke-prone spontaneously hypertensive rats. A serial section study.

The relationship of the vascular changes to the cerebral lesions has been studied using serial sections of the brains from five cases of the stroke-prone spontaneously hypertensive rats. Infarction was observed in a form of microinfarct related to single or plural occluded arterioles in the brain and subarachnoid space. Though most arterioles with fibrinoid necrosis of the wall were occluded with thrombus, infarct, which was obviously related to the occluded arterioles, was verified only in a few occasions. It was proved that infarction did not develop in all the areas irrigated by the occluded arterioles, and the regional circulation was assumed to have been maintained by the collateral circulation. There was rarefaction of the neutrophil with preservation of the neurons in the cortex around the vascular changes, such as fibrinoid necrosis of the wall. Widespread rarefaction and cyst formation were observed in the subjacent white matter, which were more marked in the vicinity of the vascular changes in the cortex. These histological changes were interpreted to be the tissue degeneration secondary to edema.