Double immunostainings of embryoid bodies sprouts for CD31, von Willebrand factor (vWF) and NG2 proteoglycan. CJ7 ES cells were allowed to differentiate in the presence of angiogenic growth factors (VEGF+FGF2) added at day 0. EBs angiogenic sprouts were analyzed at day 11 of differentiation. vWF immunoreactivity (red fluorescence) located in Weibel-Palade bodies can be observed in several sprouting CD31-positive cells (green fluorescence) (upper panels). Elongated NG2 proteoglycan-positive cells (red fluorescence) can be seen close to CD31-positive cells constituting endothelial sprouts (lower panels). Scale bar = 50 μm.