BMP signal is essential for pouch progenitor specification.(A) Time-lapse confocal images showing the specification of nkx2.3+ pouch progenitors from the pharyngeal endoderm. White arrowhead indicate the mCherry+/GFP+ cells in Tg(nkx2.3:mCherry;sox17:GFP) embryos. Scale bar, 20 μm. (B) Detection of p-Smad1/5/8 in Tg(sox17:GFP) embryos at the 6-somite stage. Representative dorsal confocal images were shown in the left three panels. Boxed areas are enlarged in the right upper panels. The orthogonal sections taken from the boxed areas were shown in the right lower panels. Arrowheads indicate the endodermal cells with p-Smad1/5/8 expression. Scale bars, 50 μm. (C-D) BMP signal inhibition impairs pouch progenitor specification. Tg(nkx2.3:mCherry;sox17:GFP) embryos were treated with 10 μM DMH1 from bud stage to the 10-somite stage. Representative confocal images were shown in (C). Scale bar, 20 μm. The number of mCherry+/GFP+ cells was statistical analyzed in (D). Student’s t-test, ****P < 0.0001.
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