Ultrastructural Changes of Capillaries in Chronic Venous Insufficiency

Abstract

The ultrastructural changes of cutaneous and subcutaneous capillaries and venules in 6 cases of severe, chronic venous insufficiency were examined. The findings in all cases consisted of numerous and characteristic alterations of the vessel wall structure and of the pericapillary space which are supposed to be due to the increased intravenous pressure. The intercellular spaces are enlarged to wide channels through which erythrocytes pass into the perivascular spaces. Microvesicles occur in great numbers, they are arranged in chain-like formations and seem to come together to form transendothelial channels. Around the capillaries, edematous fluid with proteins and erythrocytes accumulates. Phagocytosis of erythrocytes, siderosomes and collagen fibrils by macrophages is observed. Within the endothelial cells there is an abundance of Weibel-Palade bodies and of multivesicular bodies. The former are frequently seen in contact with the luminal cell membrane. Weibel-Palade bodies are believed to be involved in the clotting mechanism.