Movie 1.

Normal secondary sprouting in a wild-type (WT) embryo. Time-lapse recording in the trunk of a Tg(kdrl:EGFP); Tg(lyve1:DsRed) WT embryo from 36 hpf taken every 30 min by confocal microscopy. This Tg embryo expresses EGFP (green) in all endothelial cells (ECs) and DsRed (magenta) in venous and lymphatic ECs. Elapsed time (h:min:sec). Lateral view, anterior to the left. Secondary sprouts from the posterior cardinal vein (PCV) migrate to the horizontal myoseptum to form the parachordal lymphangioblasts (PLs), a pool of lymphatic precursors.