The morphological changes of the endothelium to venous stasis as observed under the scanning electron microscope.

In this study using the pig, venous stasis is produced artificially by placing a pneumatic cuff around the hind leg of the anaesthetised animal and the cuff inflated intermittently. The period of stasis is three hours. The leg vein distal to the cuff is biopsied before and at intervals after the onset of stasis. The endothelium of the vein is examined under the scanning electron microscope. These findings suggest that venous stasis has a traumatic effect on the endothelium and cell injury is demonstrated within three minutes of the onset of stasis. With increasing period of stasis the endothelial cells are desquamated resulting in the exposure of the subendothelial basement membrane and collagen fibres. This is followed by aggregation of platelets and fibrin. It is postulated that the effect of venous stasis on the endothelium is a primary factor and may be important in the aetiology of clinical thrombogenesis.