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Fig. 5 Absence of filopodia decreases migration velocity but does not affect guided migration. (A-D) Tg(Fli:GFP)y1 zebrafish embryos treated with 0.4% DMSO (A) or 0.08 μg/ml Lat. B (B) from 24 to 47.5 hpf. (C) Length of ISVs between the yolk end and tail at 48.5 hpf. DMSO, n=44 embryos; Lat. B, n=39 embryos. (D) Proportion of connected DLAV segments per embryo at 48.5 hpf. DMSO, n=43 embryos; Lat. B, n=38 embryos. (E-K) Tg(Fli1ep:Lifeact-EGFP) embryos treated with either 0.4% DMSO (E,F) or 0.1 μg/ml Lat. B (H-J) from 24 hpf and imaged from 30 hpf. (G,J) Kymographs of ISVs in E and H (boxed regions) showing migration from 30 to 42 hpf. (K) Leading edge velocity of ISVs migrating above the horizontal myoseptum. Dotted lines indicate mean velocities. Negative values indicate sprout retraction. DMSO, n=5 ISVs, n=2 embryos; 0.1 μg/ml Lat. B, n=8 ISVs, n=3 embryos. (L) Average tip cell nucleus velocity per ISV below, at and above the horizontal myoseptum of embryos treated with 0.4% DMSO or 0.1 μg/ml Lat. B. DMSO, n=7-9 nuclei, n=3 embryos; 0.1 μg/ml Lat. B, n=7-10 nuclei, n=3 embryos. (M) Proportion of ECs that arise from cell division and migration from the dorsal aorta during 13.5 hours of ISV development in DMSO-treated and 0.1 μg/ml Lat. B-treated embryos. 14-15 ISVs/treatment; three embryos/treatment. (N) Migrating front of an ISV from a Tg(Fli1ep:Lifeact-EGFP) embryo treated with 0.08 μg/ml Lat. B from 26 hpf. Arrows point to clusters of F-actin formed at the leading edge of the tip cell. Arrowheads indicate lamellipodia. Time indicates hours:minutes after addition of the drug. *P<0.05, **P<0.005, ***P<0.001, ****P<0.0001. Error bars represent s.d. Scale bars: 500 μm in A,B; 10 μm in E-J,N.