Figure 6: Endothelialization of of the surface of occlude. (a) Eight weeks after the procedure, the surface of occluder was lined with a layer of sparse endothelial cells (scanning electron micrographs 2,000); (b) paving-stone-like arranged endothelial cells cover completely the surfaces of devices at 12 weeks (scanning electron micrographs 2,000); (c) positive immunohistochemical staining (white arrow) for CD34 in superficial cells of the neointima at 12 weeks after implantation (original magnification ).