Ischemic carotid endothelium. Scanning electron microscopical studies.

The normal luminal surface and the effect of ischemia on the endothelium of the common carotid arteries of rhesus monkeys were examined by scanning electron microscopy. Clamps were placed proximally and distally on the right common carotid arteries, totally occluding the vessels for periods ranging from five minutes to four hours. The clamps were then removed and fixation carried out by intravascular perfusion. The contralateral sham-operated carotids, as well as those from unoperated animals were used as control specimens. The most obvious effect of ischemia was the appearance of conical, crater-like defects in the cytoplasm of endothelial cells. Such "craters" were observed following as little as 15 minutes of ischemia, were much less frequent in sham-operated vessels, and were not seen in the unoperated control specimens.