Fig. 4

Newly differentiating angioblasts and EC proliferation contribute to the posterior circulatory loop. Maximum intensity projection of Tg(fli1:nEGFP)y7; Tg(fli1:LIFEACT-EGFP)mu240; Tg(fli1:dendra2) triple-transgenic embryos labelling ECs (white) and photoconverted ECs (red). (A) ECs photoconverted at 32 hpf. Scale bar: 10 μm. (B,C) Photoconverted ECs re-imaged at 72 hpf. Scale bar: 30 μm. (B′,C′) Few ECs contain photoconverted dendra2 (blue arrowheads). Scale bar: 10 μm. (D) ECs photoconverted at 52 hpf. Scale bar: 10 μm. (E,F) Photoconverted ECs re-imaged at 72 hpf. Scale bar: 20 μm. (E′,F′) Many ECs containing photoconverted dendra2 (blue arrowheads). Scale bar: 10 μm. (G) Quantification of ECs photoconverted at 32 and 52 hpf and their contribution to the posterior circulatory loop at 72 hpf. Paired t-test (**P=0.0013); ns, not significant. Data are mean±s.d. n=5 embryos (32 hpf), n=6 embryos (52 hpf). (H) Photoconversion of terminal cells in the sprouting PCV at 50 hpf. Scale bar: 10 μm. (I) Photoconverted embryos re-imaged at 72 hpf. Scale bar: 10 μm. (J) Quantification of photoconverted cells at 72 hpf. Paired t-test (***P=0.0002, n=15). (K-P) Still images at indicated time points from (K-M) Movie 12 and (N-P) Movie 13. Imaging is from 30 to 55 hpf. Scale bar: 40 μm.