Fig. 4.

Endothelial cells undergo tubulogenesis when cocultured with cardiac myocytes. At 14 days of coculture, endothelial cells are observed to form capillary-like structures that are closely associated with other cells types. The arrowhead points to an elongated oval nucleus in an endothelial tube. The white arrow points to an endothelial cell that is not in a tube and has a round nucleus. Red, QH1 (endothelial marker); green, phalloidin (F-actin) in the Day-14 panel; blue, DAPI (nuclei). At 28 days of coculture, CM (MF20-positive, green) remains closely associated with these capillary-like endothelial tubes.