Fig. 1

Blood flow controls vascular remodeling of the trunk. Panels in (b) and (d) show lateral images of zebrafish embryos at 60 hpf with anterior side facing left. Venous ECs are labelled with mCitrine and arterial ECs are labelled with mCitrine and tdTomato. Orange arrows indicate the direction of blood flow, red arrows point to arterial ISVs and red brackets highlight regions of venous ISVs without arterial ECs. Scale bars are 25 μm. The numbers are averages ± SEM from at least three independent experiments with a minimum of n = 25 animals per conditions per experiment. P < 0.001. a Schematic overview of intersegmental vasculature remodeling. DA dorsal aorta, PCV posterior cardinal vein, DLAV dorsal longitudinal anastomotic vessel, ISV intersegmental vessel. b Flow of blood was reduced by administering 3x MS222 at indicated time point. c Percentage of venous ISVs in embryos with reduced blood flow. d Viscosity of blood was reduced by morpholino knock down of gata1a or tif1γ which are required for the formation of erythrocytes. Erythrocytes are marked by dsRed. e Percentage of venous ISVs in embryos without erythrocytes