Venous wall ultrastructure in generalized venomegaly.

The ultrastructure of the v. colica sinistra in a case of generalized vasomegaly in man was examined. Elastic material was found in three forms: as a lightly osmiophil amorphous material bordering on myocytes, as a highly osmiophil elastic membrane, and as highly osmiophil slim elastic fibres of different orientation in the tunica media and adventitia. The slightly osmiophil elastic material is assumed to be newly formed by pinocytotic activity of the myocytes. The highly osmiophil elastic material indicates its impairment. No typical atherosclerotic changes were found in the examined vein. Based on a comparison with previous findings in the case of vasomegaly of the a. mesenterica inferior, the authors conclude that the venomegaly phenomenon is connected with degenerative changes in the elastic material of the vessel wall.