Scanning electron microscopic study of hyperacute rejection in the inbred rat

Twenty skin-presensitised Lewis rats received kidney transplants from (Lewis X BN)f1 rats. Two grafts each were withdrawn at intervals from 1--120 min and examined using a scanning electron microscopic (SEM). A series of Lewis to Lewis isografts served as control. In hyperacute rejection at just 1 min spider-like fibrin fibres and platelets could be observed in small arteries, where the endothelium was severely altered. In these regions at 2 and particularly 5 min a fibrin network often contained platelet aggregates, mechanically altered erythrocytes as well as different kinds of leucocytes. This coagulation process progressed with time and resulted in a complete vascular occlusion at 30--60 min.