Id2, Id3, Foxc2 or Snail1 are necessary for development of vascular lineages. dsRNAs or siRNAs were electroporated into the presumptive lateral DM at E2 and embryos re-incubated for 40 hours. (A) dsRNA against LacZ was co-electroporated with a GFP serving as control (N = 17). Note localization of labeled progeny in myotome (M), ventral sclerotome (Scl) and cardinal vein (CV, arrows). (A’, A”) Magnification and channel breakdown of CV (dotted box in A). Arrows point to Desmin+/SMA + SM cells. (B) dsRNA to Id2/3 (N = 5), (C) dsRNA to FoxC2 (N = 16). Note the presence of labeled progeny in myotome and/or DM and their absence in blood vessels. (D) Quantifications of labeled cell distribution (mean ± SEM, and see also Additional file 4: Figure S4B). (E) Control siRNA was electroporated as in A-C. Labeled progeny are both in myotome and cardinal vein (CV) (arrows, N = 4). (E’, E”). Magnification and channel breakdown of CV (dotted box in E). Arrows point to Desmin+/SMA + SM cells. (F) siRNA to Snail1 inhibits cell migration and SM development while labeled cells remain in the ventro-lateral lip of the DM (N = 4). Endothelial cells were visualized with the Qh1 antibody (blue). (G) Quantifications of labeled cell distribution (mean ± SEM, and see also Additional file 4: Figure S4C). *P ≤0.05; **P ≤0.01 compared to controls. Lateral DM is outlined with a dotted line. Bar: (A-C) 37 μm; (A’,A”) 15 μm; (E,F) 50 μm; (E’,E”) 25 μm. Des, desmin; DM, dermomyotome; dsRNA, double-stranded RNA; E, embryonic day; SEM, standard error of the mean; SMA, smooth muscle actin.