Movie 3.

Left, still images of Tg(fli1a:EGFP) showing the endothelial plexus of two separate fish, both at the 6 bony ray stage, immediately prior (top) and after (bottom) the formation of the dorsal loop connecting the posterior axial vessels with the developing plexus within the caudal fin. Right, DIC video of blood flow at these two stages. White arrows indicate the developing dorsal loop. Time is displayed as MM:SS. Scale bar, 50 μm.