Evaluation of the cardiovascular structure following norflurazon treatment. (A) Captured images of flk1:eGFP zebrafish at 96 h post-fertilization (hpf). White arrow: central artery (CtA). Yellow arrow: bulbus arteriosus (BA). Blue arrow: sinus venosus (SV). Scale bar represents 300 μm. (B) Density of the brain vasculature determined with an image of norflurazon-treated flk1:eGFP zebrafish. The ‘Area’ tool in ImageJ was used to quantify the area occupied by blood vessels. (C) SV-BA distance quantified with an image of norflurazon-treated flk1:eGFP zebrafish using the ‘Length’ tool in ImageJ. Asterisks denote the significance level: **p < 0.01 and ***p < 0.001.