Scanning Electron Microscopic Observations on the Luminal Surface of the Rabbit Common Carotid Artery Sublected to lschemia by Arterial Occlusion

Abstract

Abstract• The scanning electron microscope (SEM) has been employed to study the effects of ischemia on the luminal surface of the common carotid artery. Fifteen adult rabbits were lightly anesthetized and the common carotid arteries surgically exposed. The right carotid artery was occluded with a single Heifetz clip for five minutes (five animals), 15 minutes (five animals), and 30 minutes (five animals). Following removal of the clip, the animals were immediately perfused with glutaraldehyde and the arteries excised and prepared for critical point drying. Four additional rabbits were perfused following the same method with no surgical procedures performed in the neck. Normal aortas were also examined. The nature and frequency of endothelial cell alterations were determined by analysis often randomly selected SEM fields. Examination of the endothelial surface of arterial segments distal to the occluding clip revealed the presence of numerous "crater-like" defects as well as outpouchings or "balloons." The numbers of craters and balloons were significantly increased in the ischemic (distal) arterial segment as compared to either proximal or sham-operated control segments (P < 0.001). These endothelial cell alterations were never observed in random micrographs of arterial segments taken from unoperated control animals, but were seen at the ostia of some intercostal arteries of the aorta. It is suggested that these craters and balloons could cause interference with blood flow and the formation of platelet thrombi by their protrusion into the lumen, as well as alteration of the permeability of the arterial intima.

Scanning electron microscopic study of endothelial cells of cerebral arteries from spontaneously hypertensive rats.

“…The craters seem to be ruptured or collapsed balloons, as Kawamura et al 13 have pointed out, because transitional forms of both conditions and the concave surface of craters occasionally revealed plasmalemmal pits and microvilli exactly as seen on the endothelial surface. Nelson et al…”

Endothelial cell damage and thrombus formation after partial arterial constriction: relevance to the role of coronary artery spasm in the pathogenesis of myocardial infarction.

“…We have shown previously that injury appearing as craters and balloons on SEM represents protruding blebs and vacuoles as seen with transmission electron microscopy.6 ' These alterations have been reported after a wide variety of injurious stimuli as well as "&spontaneously" at branch orifices,8 suggesting that these alterations represent a nonspecific reaction of endothelial cells to injury. 6 We have demonstrated that the carotid or coronary arteries that were subjected to 40-60% reduction in luminal diameter (resulting in no substantial change in the rate of distal blood flow) showed endothelial desquamation and thrombus formation only on the proximal slope ( fig. 1, segment 3), particularly in the area just proximal to the point of maximum constriction figs.…”

Preparation of vascular endothelium for scanning electron microscopy: a comparison of the effects of perfusion and immersion fixation

“…Hoff, 1970;Shimamoto & Numano, 1973;Kawamura et al, 1974;Nelson et al, 1975;Gertz, Rennels & Nelson, 1975). The transmission electron microscope (TEM) has permitted the identification of fine structural changes within endothelial cells and intercellular junctions.…”