Fig. 10. ß-catenin protein is localized in the nucleus at the correct time and place to endogenously regulate squint expression. ß-catenin protein was detected by immunohistochemistry in whole-mount assays, after which embryos were sectioned. Arrows in B-D indicate boundary between blastomeres and the yolk syncytial layer (YSL). (A) ß-catenin in the nucleus of a marginal blastomere at 2.25 h (128-cell stage), the earliest stage detected. (B,C) Nuclear ß-catenin is observed in dorsal blastomeres in embryos at 3 h (1000-cell stage), both in the enveloping layer (B,C), and in the deep layer (B). (D) ß-catenin accumulates in nuclei of the dorsal YSL at 3.3 h (high stage), but it is also seen in dorsal blastomeres. ß-catenin was associated with membranes of blastomeres at all stages examined, consistent with its role in cell adhesion. Dorsal is towards the right.