Angiogenic neovessels express arterial and venous genetic markers.

<p>A–C, Confocal images (Z-projections) of angiogenic neovessels in tMVC implants during the sprouting angiogenic phase (week 1 post-implantation) obtained from (A) <i>Efnb2</i>- or (B) <i>Ephb4</i>-reporter mice. Microvessels were identified by labeling endothelial cells with TRITC-conjugated GS-I lectin (red). <i>Ephb4</i>-driven LacZ expression shown in panel B was detected with an anti-β-galactosidase-FITC antibody. C, Determination of the % fraction of angiogenic neovessels positive for either the <i>Efnb2</i>- or <i>Ephb4</i>-reporter in tMVCs prepared as in A and B. D, Co-expression of the <i>Efnb2</i>-reporter gene and EphB4 in individual angiogenic neovessels in 1 week tMVC implants prepared from <i>Efnb2</i>-reporter mice (green) and immunostained with an anti-EphB4 antibody (red). Scale bar in all panels = 100 mm. E, Real-time PCR measurement of mRNA expression of EphrinB2, EphB4, COUP-TFII, Delta-like4 (Dll4), Jag1 and Notch4 genes in freshly isolated, specified microvessels (mature) and angiogenic neovessels in tMVCs (angiogenic). * p<0.05, n = 3 by Student's t-test.