Scanning electron microscope study of human veins and aorta-coronary artery vein grafts.

Scanning electron microscope study of two vein grafts which were removed after 50 months of implantation as aorta-coronary artery vein grafts showed considerable subendothelial thickening, which consisted of relatively cell-poor fibrous layer. In one of the grafts the endothelial surface was intact; the second graft showed focal loss of endothelial cells. Sections of two fresh human veins, studied prior to their insertion as aorta-coronary artery vein grafts, have shown that they retained an intact endothelial layer. A third fresh vein, however, showed focal damage with missing endothelial cells and adherent fibrin.