Fig. 1. Effect of Ang-1 and Ang-2 on angiogenesis (A) and mural cell recruitment (B) in the rat aorta model. (A) Angiogenesis was measured by counting branch points under light microscopy in the living cultures. Notice that Ang-1 and Ang-2 promoted branching morphogenesis of aorta-derived microvessels in a dose-dependent fashion. Bars represent the SEM (n=4). ^*, P<0.05; ^**, P<0.01. (B) Mural cell recruitment was evaluated by counting the mural cells of the ten longest microvessels of each culture at day 7, under phase-contrast microscopy. Notice that Ang-1 (0.67 µg ml^-1), Ang-2 (0.67 µg ml^-1) and the Ang-1/Ang-2 combination stimulated mural cell recruitment. Soluble Tie2 blocked stimulation of mural cell recruitment by Ang-1 and Ang-2 used alone or in combination. Bars represent the SEM (n=40). ^*, P<0.01; ^**, P<0.001.