Immunohistochemical images of explants 1 week after surgery (patent lumens). Staining for smooth muscle actin (A, B), laminin (C, D), factor VIII (E, F) and VWF (G, H). Surrounding tissue has invaded the outer collagen layer of the natural graft (A). Endothelial cells on a laminin-positive layer (C, D). Endothelial cells positive for VWF and factor VIII (E-H). VWF-rich depots in the collagen porous film (insert E). Arrows indicate positive staining (C-E), and dotted lines indicate boundary between collagen scaffold and surrounding tissue (A), and anastomosis (B, distal). Bars present 200 µm (A-F) and 50 µm (G, H, and insert of E).