Histopathology of microvenous repair.

The histopathology of microvascular repair was investigated in the femoral vein of the rat. Previous microvascular repair studies have primarily involved arteries, giving little insight to similar processes in veins. In our study, 36 rats with an average weight of 440 gm were randomly assigned to experimental groups of 1 hour, 24 hours, 2 weeks, and 4 weeks after repair. Histological evaluation of the suture site included the use of light, scanning electron, and transmission electron microscopy. Endothelial loss was observed in all 1-hour specimens. Extensive inflammatory response appeared in 2-hour specimens. Re-endothelialization of the intima was achieved in all animals by the 2-week time interval. At 4 weeks, the animals exhibited evidence of medial regeneration of smooth muscle cells. This was predominantly occurring between adjacent suture sites. Minimal subintimal hyperplasia was localized at the suture site itself in both 2- and 4-week specimens.