Observation of arterial and venous thrombus formation by scanning and transmission electron microscopy.

BACKGROUND

In order to examine the process of thrombosis formation in artery and vein, the reactions of the arterial and venous endothelial surfaces were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in the photothrombosis model.

MATERIALS AND METHODS

Thirty-nine rats were divided into the following 4 groups: 1) Sham group (n = 5) without illumination, 2) group A (n = 10) irradiated for 1 min, 3) group B (n = 10) irradiated for 5 min, 4) group C (n = 14) irradiated for 10 min at the level of the left common carotid artery and internal jugular vein.

RESULTS

SEM provided no evidence of damage or adhesion of blood platelets to the endothelium of either the artery or vein in shams or group A animals. In group B, evidence of damage to endothelial cell membrane (e.g., plasmalemmal pits, crater-like structures associated with tears between endothelial cells, and decreased number of microvilli) was obtained in the arterial wall but not in the vein. In group C, there was extensive or widespread adhesion of blood platelets and other cells, tears between arterial endothelial cells, and a decrease in the number of microvilli in the artery but not in the vein (p < 0.05).

CONCLUSIONS

Cell membrane injuries, tears between the endothelial cells, and endothelial detachment occur before adhesion of blood platelets and thrombus formation in the blood vessel occlusion model by photochemical reaction. These changes occur significantly earlier in the artery than in the vein.