Figure 8. The observation of endothelial sprouting cultured on the 3D printed A-SA-Gel hydrogel scaffolds after 4 days; (A-F) Fluorescent microscope images of endothelial sprouting and sprouting of neovessels network: (A) the formation of microvascular network, (B) a microvessel of endothelial cells like a bridge, interconnected between adjacent sides, (C) branched microvascular network, and (D-F) the formation of robust neovessels with open lumen; (G) Quantitative analysis of the diameter of endothelial cells’ microvascular network; (H) Quantitative analysis of the diameter of neovessels; (I) Quantitation of the sprout length.