Fig. 2. ß4 integrin is expressed by endothelial cells of the vasa vasorum but not by endothelial cells lining the lumen of human saphenous vein. (A) Frozen section of human saphenous vein stained with Hematoxylin and Eosin; the asterisk indicates the lumen of the saphenous vein. The dashed box shows an example of the region chosen for higher magnification immunohistochemical imaging in BE. Cross sections of saphenous vein were stained with antibodies to vWF (B), marking endothelial cells lining the main lumen (arrow) and the vasa vasorum (arrowheads) and 3E1 to ß4 (D), selectively staining endothelial cells of the vasa vasorum (arrowheads). (C,E) Control immunostaining in the absence of primary antibody, for B and D, respectively. Scale bars: (A) 500 µm; (B-E) 200 µm.