The structure of the heart and blood vessels that were damaged by mecoprop-p. (A) Transgenic flk1:eGFP zebrafish models were observed using an upright fluorescence microscope. The structural abnormalities in the heart and aortic arches are shown. The second panels are extended images of white boxes. Scale bar: 300 µm. (B and C) The density of the aortic arches and the distance between the SV and BA were calculated using ImageJ software. (D) The heart rate per minute was measured manually (**p < 0.01 and ***p < 0.001).