Fig. 2. Expression of vascular markers in embryoid bodies (EBs). ES cells were differentiated into EBs, fixed on day 5 or 8 and stained with antibodies to CD31, VEGFR-2 and VE-cadherin. When indicated, differentiation medium was supplemented with 10 ng/ml human rVEGF-165. (A) While the CD31 antibody stained cell clumps in untreated 5- and 8-day-old EBs, the addition of 10 ng/ml rVEGF promoted the organization of CD31⁺ cells into pseudo-vascular structures. (B) Vascular endothelial networks in 8-day-old EBs were co-stained for CD31 (red) and VEGFR-2 (green), and similar structures also expressed VE-cadherin (green). Bar, 100 µM.