Fig. 2

Fig. 2

Foxi1 requirement in the ectodermal Wnt4a expression during pouch formation. (A, B) Fluorescent in situ hybridization showed fgf3 expression (green) in the posteriormost three pouches (arrows in A), with increased expression in the newly forming pouch (asterisk in A) in wild-type embryos. While fgf3 expression was observed in the posteriormost two pouches (arrows in B), the intensity in the newly forming pouch (asterisk in B) was weaker than that of wild-type embryos (compare to asterisk in A). (C) Double fluorescent in situ hybridization showed colocalization of wnt4a (red) with foxi1 (green, arrows in C) but not with her5-positive pouch endoderm labeled by GFP immunohistochemistry (blue). (C’) Green and red channels. (C”) Green channel only. (C′′′) Red channel only. (D, E) Fluorescent in situ hybridization for wnt4a (green). In the facial ectoderm, foxi1 mutants had significantly reduced wnt4a staining, compared with wild-type embryos (lines in D and E). (F, G) Fluorescent in situ hybridization for foxi1 (green). Similar foxi1 expression in the pharyngeal regions was observed in wnt4a mutants (G), compared with wild-type embryos (F). (H, I) Fluorescent in situ hybridization for fgf8a (green). (H) In wild-type embryos, fgf8a was expressed in mesoderm (line) adjacent to outgrowing pouches as well as in the otic vesicle (arrow). (I) In foxi1 mutants, fgf8a expression was observed in the mesoderm (line) as well as in the otic vesicle (arrow), even though fgf8a expressing mesoderm was disorganized compared to wild-type mesoderm. Scale bar: 40 µm.