Movie 3.

Analysis of blood flow in the PCV of WT and tie1 mutant embryos. High-speed time-lapse imaging in the trunk of Tg(kdrl:EGFP);Tg(lyve1:DsRed) WT and tie1^-/- embryos (45 hpf) injected with PEG-coated fluorescent microspheres (PEGcoated FM, magenta) taken at 200 frames/second. Elapsed time (sec). PEG-coated FMs in the PCV were tracked (yellow lines) to measure the velocity (WT, 474 μm/s; tie1^-/-, 460 μm/s). The flow velocities of these two embryos are comparable and correspond to blue dots in Fig. 3F,G. Secondary sprouting of the same embryos is shown in Fig. S6C.