A scanning electron microscopic (SEM) study of the re-endothelialization of the carotid end-to-side anastomosis in the rat.

A carotid end-to-side anastomosis was made on 25 male Wistar rats (mean weight 197.8 g). At different time intervals, from 0 to 21 days after the operation, the animals were sacrificed. The anastomosis was exposed, the aorta was cannulated, and the animals were perfused at a constant pressure of 80 mm Hg with a 2 1/2% glutaraldehyde solution. The anastomoses were taken out for further SEM and light microscopic (LM) study. The SEM results indicate that after the acute platelet-fibrin reaction in the first 48 hours the suture line itself becomes reendothelialized after 4 days. On the stitches, however, (EthilonR 11 X 0, 2871 G, BV7 needle) after two days a cellular population was seen, consisting of leucocytes transforming into flattened cells. The morphology of these cells and their role in the regeneration of endothelium is discussed. This study gives evidence to the possibility of a blood-borne genesis of endothelial cells in vivo.