Perivascular hemorrhagic lesions in temporal cortex following cerebral infarction (a morphological study)

Abstract Perivascular hemorrhagic lesions were produced in squirrel monkeys following transorbital occlusion of the middle cerebral artery. The respective periods of occlusive insult were 7.5, 15, 30 min, and 1 hr. After 1 wk of postoperative care, the animals were prepared for morphological study by a total body perfusion technique. Small hemorrhagic loci were observed grossly in the temporal cortex. By light microscopy these erythrocytic patches occupied predominantly a perivascular position, however, some interparenchymal clumps were also present. Ultrastructurally, separation of erythrocytes from the capillary components was noted. Interventing astrocytic end-feet were not swollen, nor did they show other morphological abnormalities (lysosomal increase, glycogen depletion, etc.). Capillaries were intact and ultrastructurally normal. Increased vacuolization was common in tissue adjacent to the erythrocyte clumps. Since no morphological changes were found in the microvasculature, it was concluded that diapedesis and extravasation had resulted from permeability changes in larger vessels.