Figure 4. Animal model and grouping A 10 × 8 cm (length x width) skin flap was designed symmetrically along the middle line of the abdomen.

(A) Control group: single side of inferior epigastric artery and vein was preserved as a physiological flap. The circles including four ones located in 1.5 cm away from both sides and one in the middle indicate the location for blood flow measurement and the black square in the center area shows the specimen harvested for water content study and the area between the red square and black squared is harvested for metabolite analysis.(IEV, inferior epigastric vein; IEA, inferior epigastric artery; EIA, external iliac artery; FA, femoral artery.) (B) Experimental group I: one side of femoral artery was freed and transferred reversely to anastomose with the proximal end of the thoracoepigastric vein, simply leaving the distal thoracoepigastric vein of this side intact to provide venous outflow and all other arteries and veins connected with the flap were ligated.(TEV, thoracoepigastic vein; FA, femoral artery). (C) Experimental group II: similar to experimental group I, but additionally leaving the contralateral distal side of thoracoepigastric vein intact. (TEV, thoracoepigastic vein; FA, femoral artery). (D) Experimental group III: similar to experimental group II, but additionally leaving the contralateral proximal side of thoracoepigastric vein intact. (TEV, thoracoepigastic vein; FA, femoral artery).