Fig. 1. Mutant embryos develop to blastocysts but exhibit a phenotype at early gastrulation. Immunohistochemical detection of ß-catenin in wild-type (A) and mutant (B) ovaries revealed enhanced cytoplasmic localization of ß-catenin in mutant oocytes. (C) Genotyping of single oocytes from ß-catEx3flox/+;cre/+females by PCR demonstrates the efficient deletion of the floxed exon 3 of the ß-catenin gene by the oocyte-specific cre-recombinase; tail DNA from the same females was used as the control. (D) Western blot of cell lysates from mutant and wild-type (R1) ES cells shows the expression of the stabilized form of ß-catenin in the mutant cells. (E-H) Immunofluorescent detection of ß-catenin in wild-type (E), and mutant (F) blastocysts, and simultaneous detection for E-cadherin (green) and Oct4 (red) (G, wild type; H, mutant) revealed no differences between these embryos. (I-J) Phenotype of mutant (J,K) and wild-type (I) E6.5 embryos revealed that the epiblast of mutant embryos varied, being small or disorganized. Scale bar: 50 µm.