Dorsal view of zebrafish embryos illustrated cardiac system prior to and after pigmentation removal.

<p>(a) Pigmentation opacifies internal organ systems at 120 hpf. (b) Treatments with PTU beginning at 10 hpf prevented pigment formation, allowing for clear organ visualization. (c) PTU-treated zebrafish heart observed under bright field microscope at 120 hpf. Despite visualization of outer wall, inner wall is poorly demarcated. (d) The use of transgenic <i>Tg</i>(fli1a:EGFP)<i>y1</i> embryos allows for clear delineation of inner wall for reconstructing the CFD model. (e) <i>Tg(gata1:dsRed)sd2</i> transgenic zebrafish allows to visualize the blood particle in order to take velocity by particle tracking technique. A, atrium; V, ventricle; B, bulbus arteriosus.