Fig. 2. Confirmation of the GeneChip results by whole-mount in situ hybridization. (A-I) Late-gastrula stage wild-type (wt) and conditional ß-catenin mutant (CKO) embryos hybridized with the indicated probes. All embryos are depicted in a lateral view, anterior to the left. (A-H) Axin2, Wnt3a, Wnt8, Frzb1, Notch1, Dll1, Gbx2 and Hoxb1 are all expressed in the primitive streak of wild-type embryos, but are downregulated in conditional ß-catenin mutants to varying extents. (I) Sox2 is normally expressed in the extraembryonic chorion and anterior epiblast in wild-type embryos at this stage. The expression in the extraembryonic region is unaffected in mutant embryos, but the whole epiblast expresses Sox2.