The NA/EE-mixture induces morphological damage in zebrafish embryos at 6 hpf, 24 hpf, 48 hpf and 72 hpf in a stage-sensitive manner. Embryos at 6 hpf, 24 hpf, 48 hpf and 72 hpf were treated with either DMSO or NA/EE-mixture (NA 12.5 μg/mL + EE 25 ng/mL), incubated for 24 hours then fixed and imaged. (A–H) Embryos at 6 hpf (A,B), 24 hpf (C,D), 48 hpf (E, F), 72 hpf (G,H) treated with DMSO (A,C,E,G) or NA/EE-mixture (B,D,F,H; n > 15 for all time points and conditions). Note: twisted spine (grey arrowhead); smaller eye (white asterisk); yolk sac anomalies/oedema (grey arrow), bent spine (black asterisk) and pericardial defect (black arrowhead). Scale bars: 250 µm.