Scanning Electron Microscopy (SEM) of the Endothelium of Canine Vein Segments Prepared for Surgery

Abstract

In order to assess the integrity of large areas of endothelium in canine veins, segments have been studied by SEM. This technique enables one to accurately assess the surface morphology of relatively large areas of vein endothelium. Canine jugular veins were fixed in 4% glutaraldehyde, critical point dried in liquid CO2, and then coated with gold and palladium for SEM. Control veins (Fig. 1) revealed a flat, smooth sheet of polyhedral endothelial cells with slightly protruding nuclei and regular cell boundaries. The luminal surface was free of any defects, though occasional adherent blood cells were noted. When the vein was stripped of surrounding adventitia and left in situ with normal intraluminal blood flow for two hours (Fig. 2), there was a moderate increase in the number of blood cells sticking to the endothelial surface, but no evidence of endothelial cell sloughing or separation. Studies employing en face serial sections visualized by Nomarski differential interference contrast microscopy (DIC), and thin sections studied by transmission electron microscopy (TEM) revealed no evidence of endothelial or medial necrosis, but foci of extravasated erythrocytes and neutrophils were noted within the media of the veins from which the adventitia had been stripped.