1988 Volume 28 Issue 2 Pages 109-116
Sequential structural changes in endothelial cells after temporary arterial clipping were studied by both scanning and transmission electron microscopy. A Heifetz clip with an occlusive pressure of 120g was applied to the carotid arteries of 33 Wistar rats for 30 minutes. The animals were sacrificed at the following intervals after clipping: 0, 1, 3, 6, and 24 hours and 3, 5, 7, 14, and 30 days. Immediately after removal of the clip, there was severe endothelial desquamation, with platelets adhering to the exposed subendothelium. Three days after clipping, repair of the endothelium was accomplished by replication of adjacent undamaged endothelial cells and was completed within 1 week. Immature regenerating cells were characterized by numerous microvillous projections at the luminal surface. These projections were approximately 100 to 150nm in width and 0.2 to 1μm in length. The immature endothelial cells contained well developed rough endoplasmic reticulum and many free ribosomes but contained few Weibel-Palade bodies and pinocytotic vesicles. However, as the endothelial cells matured, pinocytotic vesicles and Weibel-Palade bodies increased, whereas microvillous projections decreased. Within 14 days of clipping, the microvillous projections had disappeared and the endothelial cells appeared normal. These data indicate that the endothelial damage caused by temporary arterial clipping does not result in thrombus or atherosclerotic lesions and is repaired within approximately 14 days.
