Abstract: To investigate the survival of expanded prefabricated flaps and its mechanism, microcirculation and ultrastructural changes. Methods: A total of 36 New Zealand male rabbits were divided randomly into expanded prefabricated, expender lined and prefabricated groups. After the femoral vascular bundles were transplanted into the subcutaneous tissues of abdomen, expanders were implanted into the deeper dartos. For the expanded prefabricated group, the expansion was carried out at 7 days postoperatively; When the expander was fully expanded at 52 days, island flaps with the prefabricated vessels as the pedicles were formed. The flaps were measured by digital recording of survival area, laser Doppler flowmetry, immunhistochemistry, light microscope and electron microscope. Results:　When compared with other groups, the blood flow enhanced; the flap survival improved; VEGF, bFGF, VEGFR and bFGFR increased； blood capillary was stronger， and the ultrastructure significantly changed in the expanded prefabricated groups. Conclusion: Expanded prefabricated flap is good in survival and safe in transplantation; the growth of VEGF, bFGF, VEGFR and bFGFR accelerates the neoangiogenesis of expanded prefabricated flaps.

Key words: Prefabrication, Prefabricated flaps, Expension, Rabbit