Fig. 3

Fig. 3

Treatment of embryos with the FGFR1‐selective inhibitor PD166866 from 36 to 96 hpf caused severe defects in thyroid morphology and volume and resulted in abnormal or absent in HAs. All embryos shown are oriented anterior to the top in the ventral views. (A) An analysis of DMSO‐treated embryos showed normal vascular development with normal thyroid morphology at 96 hpf. (B) Treatment with PD 166866 from 36 to 96 hpf caused a reduction in tg signal intensity and resulted in abnormal HAs (stubby and malformed) in 8 of 20 embryos. (C) The absence of HAs was observed in 12 of 20 embryos during 36–96 hpf drug treatment, and this occurred along with abnormal thyroid expansion. The percentage of abnormal or absent HAs in PD 166866‐treated embryos is presented in the lower right corner of B and C. Arrow: HA. *: VA. **: the absence of HA. Scale bar: 50 μm.