[An experimental study on healing processes of microarterial and microvenous transplantation. The possibility of clinical application in oral reconstructive surgery].

Sixty-three Wistar female rats, weighing from 250 to 350g were used in order to investigate patency rate and histological changes of arterio-arterial and veno-venous autografts, using the right femoral artery and vein. The left femoral artery and vein served as control. The grafts were retrieved over a period of time ranging from 4, 7, 14, 28 and 56th day postoperatively. The patency rate was checked by Hayhurst and O'Brien's method. The histological changes of grafts were evaluated by the light and scanning electron microscope. Arterio-arterial graft maintained high patency rate throughout the experiment (90.0%, 27/30). This high patency rate may be explained by revascularization immediately after anastomosis. The average patency rate in veno-venous graft was 75.8% (25/33). Patency rate in 14th and 28th day in veno-venous graft showed 100%, that seemed to be related to the early completion of endothelial cells lining of the graft. Regeneration proceeded from the preserved endothelial cells in graft as well as endothelial cells of the artery and vein. The number of preserved endothelial cells in the arterial graft was fewer than that in the venous one. Therefore, the completion of covering by endothelial cells in arterial graft was slower than that in venous graft. The obstruction in arterio-arterial graft was caused by thrombus in the rupture of vessels formed by the suture procedures. In veno-venous graft, thrombus on the exposed vessels' wall resulted in the obstruction. Subintimal hyperplasia was seen in all arterial graft. No such change was seen in venous graft. These results indicate that revascularization immediately after anastomosis, tight and atraumatic suture procedures are important for the prevention of obstruction in arterio-arterial graft and veno-venous graft.