Fig. 3

Elongation of endothelial cells derived from ES cells. a In the co-culture system with OP9 stromal feeder cells, ES-derived endothelial cells form a round colony in the presence of a low level of VEGF, which produced by OP9 cells (left panel). These cells form long elongated structures, when stimulated by a high level of VEGF (right panel). Scale bar 200 μm. b ES-derived endothelial cells form vessel-like structures in the 3D collagen gel culture. Scale bar 100 μm