[Microvalves in microvenules].

A long-lasting histological study on muscle and cutaneous-subcutaneous biopsies allowed certain observations of microvalves in venules with a diameter ranging from 80 to 200 micron. Venular leaflets originate from the vein as extroflection of the intima, made by a single layer of endothelial cells. In the patient affected by severe chronic venous insufficiency the valvular leaflets appear thickened while the wall of the venule presents sclero-hyalinotic alterations. The presence of microvalves in venules suggests a role of their incontinence in the venous insufficiency. Considering that the venular leaflets are made just by endothelial cells, a primary pathogenetic role has to be achieved to the endotheliopathy in the genesis of venous insufficiency.