The patency-rate of venous bypasses depends--beside other important factors--upon the integrity of the transplanted vessel, especially on the condition of the tunica intima. We investigated two different methods of venous storage and their on the intima. We examined 24 segments of healthy human saphenous vein and 65 segments of the inferior vena cava in the rat which had been harvested using a minimal touch technique. The veins were stored in the patients own arterial heparinized blood vs. Euro Collins solution at 4 degrees C, 20 degrees C and 37 degrees C over 15, 30, 60, and 90 minutes. As a reference we examined 11 segments of human saphenous vein which had been fixed immediately after harvesting. The stainings were performed with PAS, HE, Domagk-Elastica, and Toluidine-blue. We examined 1,181 slices by light-microscopy and used a damage score table for the documentation of the vein-trauma. No significant differences were found between human and animals veins. In the control-group the endothelium, the subendothelial layer, and the intern elastic membrane were intact in 57%, 78%, and 38%. At 4 degrees C the endothelium was intact in 31% having been stored in blood, and in 44% at Euro Collins solution. For the subendothelial layer the ratio was 48%/66%, and for the intern elastic membrane 26%/42%. At 20 degrees C we found a ratio of 55%/47% vs. 65%/58% vs. 37%/39%, and at 37 degrees C 56%/37% vs. 64%/51%/32%/38%. The factor time could be neglected up to 90 minutes. The results show that veins should be used immediately after harvesting.(ABSTRACT TRUNCATED AT 250 WORDS)