Fig. 6. Activation of the Wnt/ß-catenin pathway in the tail bud of Sfrp1^-/-; Sfrp2^-/- embryos at E8.5. (A-F) Cross sections of the posterior region in control (A,B) and Sfrp1^-/-;Sfrp2^-/- (D,E) embryos stained with anti non-phospho ß-catenin antibody. (C,F) Control staining was performed without the first antibody. hg, hindgut; mp, mesoderm cells beneath the primitive streak; np, neural plate; asterisk, non-specific staining. Higher staining intensity was observed in the hindgut and in the axial mesoderm of control embryos. A similar intensity in staining was observed in the tail bud region of Sfrp1^-/-; Sfrp2^-/- embryos, including the mesoderm, neural ectoderm and laterally located paraxial mesoderm (inside of arrowheads and in the box labelled K; E), in addition to the hindgut endoderm and mesoderm beneath the primitive streak. Scale bar: 200 µm. (G-O) Higher magnification of the regions (labeled H,K,N) indicated in B and E. The mesoderm beneath the primitive streak is outlined by the broken line in H. (I,L,O) Nuclei were stained with DAPI (4,6-diamino-2-phenylindole; blue). G,J and M show merged images of H and I, K and L, and N and O, respectively. Arrowheads in J (merged image) indicate the positions of cells corresponding to those in original images (K and L). Scale bar: 33 µm.