Highly developed, dense and organized quail coronary vasculature in the day 9 and 13 embryo. Vessels stained with DiI and color-coded based on depth in the 3D confocal image set. (a) Embryonic day 9. (b) Embryonic day 13. Posterior heart wall from the epicardium to the middle of the ventricular lumen. Two representative hearts shown with n = 4 hearts each for ED9 and ED13. Images colored with FIJI based on z-slice depth from confocal image stack. (c) Diameter of a vessel cross section after DiI perfusion. (d) Short diameter of blood cell nuclei as seen in DAPI images.