Intercellular granules and vesicles in prolonged cerebral vasospasm

Abstract

✓ Prolonged vasospasm was produced in the dog basilar arteries by introduction of fresh arterial blood or norepinephrine into the chiasmatic cistern. Myonecrosis was limited to a small number of smooth-muscle cells, and a large number of muscle cells appeared intact. The most characteristic change was the appearance of aggregated granules and vesicles in the widened extracellular space between smooth-muscle cells, particularly near the adventitia and the elastic lamina. The granules were spherical, 50 to 100 nm in diameter, often surrounded by a single membrane, and contained a dense osmiophilic core, about 40 to 90 nm in diameter. In addition, the elastic lamina often became loose and corrugated or broken.