Fig. 8. Acetaminophen (Aceta) exposure causes defects in heart development of zebrafish embryos. Experiments were performed three times. Bright-field images show atrium (a) and ventricle (v) morphology at 72 h postfertilization in (A ) dimethyl sulfoxide (DMSO) versus (B ) 5-mM acetaminophen–treated embryos. Dashed white lines outline the heart. (C ) Summary of the angle between the midline and atrioventricular canal at 72 h postfertilization in DMSO (n = 10) versus 5-mM acetaminophen–treated (n = 15) embryos. Results are shown as mean ± SD. Heart looping angle was analyzed by unpaired two-tailed Student t test. (D, E ) Confocal images showing the morphology of the heart valve in 96-h postfertilization embryos. Scale bar: 20 μm. (F ) Summary of heart valve formation in 96-h postfertilization embryos as analyzed by chi-square test. **P < 0.01. ***P < 0.001.