Evaluation of angiogenesis in delayed skin flaps using a monoclonal antibody for the vascular endothelium.

The angiogenic process in delayed and undelayed flaps was evaluated in relation to different periods of delay (6 h, 72 h and 7 days) and at different times after the definitive elevation of the flaps (48 h, 96 h and 7 days). An immunohistochemical method has been tested to stain the endothelial cells of capillaries and venules, providing a high specificity for labelling these vessels. No signs of angiogenesis were found in undelayed and 6-h delayed flaps at 48 h but there was an increase of capillaries from 48 h to 7 days after elevation of the flaps. The 72-h and 7-day delayed flaps showed signs of angiogenesis at 48 h and the capillary development went on increasing to the 7th day after definitive flap elevation (p < 0.05). The surviving lengths of these groups of flaps were higher than the control and 6-h delayed flaps (p < 0.05). These results indicate that an angiogenic process can be implicated in the physiology of the delay phenomenon.