ZFIN Image: Haerlingen et al., 2023, Fig. 8.

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Figure Caption

Fig. 8.

Refined model of thyroid precursor specification. During early somitogenesis, the anterior foregut endoderm (green) receives patterning signals (yellow arrows) from the anterior lateral plate mesoderm (aLPM). At around 18 hpf, FGF signals (blue arrows) derived from the adjacent cardiac mesoderm (red) induce Pax2a expression in endodermal cells. Up to this stage, active BMP signaling is limited to mesodermal cells. Around 23/24 hpf, a subpopulation of Pax2a⁺ endodermal cells, located closest to the cardiac outflow tract mesoderm, receives BMP signals inducing Nkx2.4b expression. Pax2a⁺/Nkx2.4b⁺ cells represent committed thyroid cell precursors, whereas Pax2a⁺/Nkx2.4b⁻ cells assume alternative cell fates.

Acknowledgments

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