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. Author manuscript; available in PMC: 2015 Jun 1.
Published in final edited form as: Dev Biol. 2014 Mar 18;390(1):1–13. doi: 10.1016/j.ydbio.2014.03.004

Figure 7. Fgf8 expression is delayed in Foxi3 mutant pharyngeal ectoderm.

Figure 7

The expression pattern of Fgf8 at 15 somites is similar to the Foxi3 expression pattern at the same stage. In 15 somite staged Foxi3 mutants, Fgf8 expression is substantially reduced and is present only in pharyngeal endoderm but not pharyngeal ectoderm. Expression of downstream transcription factor Erm is reduced in Foxi3 mutants to a few cells adjacent to the endoderm. MAPK signaling as indicated by di-phosphorylated Erk (pErk) is detectable in many fewer mesenchymal cells in Foxi3 mutant embryo arches. The level of staining in Foxi3 mutants was similar to that seen in wild type embryos incubated for 30 minutes in the MAPK inhibitor U0126 (not shown). Expression of Fgf8 partially recovers in pharyngeal ectoderm by 22 somites, but is still not expressed as broadly as in wild type embryos of corresponding ages. Scale bars are 100μm.