Fig. 5. Differentiation of arterial endothelial cells within the vascular cord. Transverse sections visualized for GFP (A,D,G,J) (green), ephrin B2 (B,E,H,K) (red) and ß-catenin (C,F,I,L) (blue). Sections shown are at the level of the 7th (A to C), 10th (D to F), and 14th somite (G to L). Arrowheads mark the ephrinB2 expression within the vascular cord. Subsets of angioblasts within the vascular cord start to express ephrin B2 at 17 hpf, and this expression later becomes restricted to the DA. NT, neural tube; NC, notochord.