Region-specific contractile response of the embryonic aorta. A) Lineage labeled 19.5 dpc aorta mounted on cannula for experimental analysis. Boxes represent regions where lumen diameters are measured. B) Example traces from aAo (gray) and dAo (black) with the addition of different vasoconstrictors, PE (phenylephrine), ET-1 (endothelin-1). Abbreviations: aAo, ascending aorta; bc, brachiocephalic artery; da, ductus arteriosus; dAo, descending aorta; lcc, left common carotid; lsc, left subclavian. Error bars represent SEM. *, p≤0.05; **, p≤0.01.