Using confocal and time - lapse imaging, the investigators were able to visualize coronary vessels developing from the endocardium, or the inner lining of the heart — specifically from the atrioventricular canal, the structure that divides the heart into compartments. (sciencedaily.com)
As expected, Venus expression was detected in the pharyngeal pouch endoderm, endocardium, inter-somitic vessels, and dorsal aorta (Figure 1D). (journals.plos.org)