Morphology of mouse aortic endothelial cells. (A) Aortic explants were cultured on top of collagen gel beads for 4 days. EC grew and migrated out of the aorta piece. (B) EC grown on collagen gel beads without migration seems to keep their original elongated morphology. (C-E) iMAECs collected after cell sorting were cultured for 24 h and imaged (C: phase contrast, D: DiI-Ac-LDL staining by fluorescence microscopy, and E: merged image). Scale bar = 50 μm.