Extended Data Fig. 2: Enhancer driven reporter activity in zebrafish.

a, At 5 days post-fertilization (dpf) zebrafish reporter lines for the zebrafish −2.1 kb prox1a and mouse −11 kb Prox1 enhancer elements drive GFP expression (cyan) in the facial lymphatic endothelium (arrowheads), including the facial valve (arrow) as demonstrated by overlapping expression with Tg(−5.2lyve1b:DsRed2)^nz101 or TgBAC(prox1a:KalTA4-4xUAS-ADV.E1b:TagRFP)^nim5 (both magenta). b, In both enhancer reporter lines at 5dpf, endothelial GFP signal (cyan) is restricted to the lymphatic vessels in the face, as shown by lack of co-expression with Tg(kdr-l:ras-cherry)^s916, which marks the venous endothelium of the primary head sinus (magenta). Additional domains of non-endothelial expression in the face appear to be induced ectopically by both enhancers. c, At 54 h post-fertilization, after sprouting of the facial lymphatics has commenced, co-expression of mouse enhancer-driven GFP (cyan) with lyve1b is observed in the lymphatic progenitors coming from two venous niches, the common cardinal vein lymphangioblasts (CCV-L, arrowhead) and the primary head sinus lymphangioblasts (PHS-LP, arrow). Asterisk indicates co-expression in the underlying PHS. Scale bars, 50 µm.