Embryos lacking both Notch2 and Notch3 have disrupted blood vessels.

<p>Hematoxylin and eosin staining of transverse sections of E11.5 embryos through the heart and midsection (A–D), descending aorta (E–H), and caudal aorta (I–L). In the <i>Notch2^−/−;Notch3^−/− (N2^−/−;N3^−/−)</i> embryos, the paired dorsal aorta is expanded in size and filled with blood (D, arrowheads). Higher magnification of blood vessels in double mutant embryos show a lack of cells surrounding the lumen (H, L). The overall structure of blood vessels appears relatively normal in the single <i>Notch2^−/− (N2^−/−;N3^+/+)</i> and <i>Notch3^−/− (N2^+/+;N3^−/−)</i> mice. Scale bar = 100 µm. (H) heart, (nt) neural tube.