Scanning electron microscopy of experimental thrombus formation in canine lateral saphena vein.

In order to evaluate the effect of urokinase on thrombus a model of experimental thrombus was formed at left lateral saphena vein of beagle dogs by an injection of canine or bovine fibrinogen and bovine thrombin. Surface and cut-surface of thus formed thrombus were observed with a field emission Scanning Electron Microscope (SEM). Despite considerable variations among dogs the thrombus decreased its volume and compactness as time passed. The proportion of deformed erythrocytes and non-erythrocyte components of thrombus increased at 6, 15 and 24 hours after thrombogenesis. Erythrocytes penetrate into spaces between fibrin sheets and covered with fibrin network. The fibrin fibrils became thick in later stages. The surface of endothelium did not alter extensively by the presence of thrombus. Natural thrombolysis occurred between 15 and 24 hours after thrombogenesis. Recannalization of the vein was monitored with X-ray angiogram and the measurement of FDP.