Fig. 7. Antagonists of the Wnt/ β-catenin pathway promote Isl1 and Nkx2.5 expression in AHF/SpM and branchial arches. (A,B) Representation of the electroporation of pCIG-sFrp2-IRES-GFP together with pCIG-sFrp3-IRES-GFP constructs between St. 8 and St. 12. Dashed line indicates the plane of the transverse sections. (C) Immunostaining for Nkx2.5 at St. 12 indicating that Nkx2.5 protein level increased (arrowhead) on the electroporated side (arrow). (D) Immunostaining for Isl1 at St. 12. GFP expression in the surface ectoderm marks cells expressing the sFrp2 and sFrp3 proteins. Isl1 level in the SpM (arrowhead) was increased on the electroporated side (n=7). (E,F) Fz8-IgG-soaked bead insertion (E, St. 8) and the same embryo 23 hours later (F, St. 14). (G-I) Transverse sections showing the location of the implanted bead (blue circle in G,I and dashed circle in H). (G'-I') Immunostaining of sections G-I. As a result of the Fz8-IgG activity, both Nkx2.5 (G',H') and Isl1 (I') levels in BA1 increased around the bead (n=4). EP, electroporation; nt, neural tube; BA1, branchial arch 1; hrt, heart; ph, pharynx.