Fig. 2. Stabilization of ß-catenin results in disruption of pancreas formation in PdxCre^early ß-cat^active mice. (A-C) Examination of pancreas gross morphology. The majority of the dorsal pancreas (dp) and ventral pancreas (vp) has been lost in PdxCre^early ß-cat^active mice (C) at E18.5. By contrast, PdxCre^late ß-cat^active pancreas morphology (B) appears equivalent to control (A) at E18.5. s, stomach; sp, spleen; d, duodenum. (D-F) Hematoxylin and Eosin staining was performed on paraffin sections from E18.5 tissue from either control (D), PdxCre^late ß-cat^active (E) or PdxCre^early ß-cat^active (F) animals. Whereas PdxCre^late ß-cat^active pancreas structure (E) is normal, the PdxCre^early ß-cat^active pancreatic remnant (F) contains very little exocrine tissue and exhibits multiple pronounced cyst structures (c). The majority of the remaining tissue appears mesenchymal in PdxCre^early ß-cat^active mutants. (G) Staining of pancreas sections for ß-catenin (green) and the nuclear co-stain DAPI (blue) reveals that ß-catenin is localized exclusively to the membrane in control animals. (H,I) Significant levels of nuclear ß-catenin can be detected in both the PdxCre^late ß-cat^active and PdxCre^early ß-cat^active mutants. Insets show increased magnification of equivalent fields in each image. Scale bars: 50 µm. (J-L) Staining for the epithelial marker E-cadherin (green) indicates the dramatic loss of epithelial tissue in the PdxCre^early ß-cat^active mutant (L) when compared with both the PdxCre^late ß-cat^active (K) and control (J). The PdxCre^early ß-cat^active cysts are lined by E-cadherin-positive cells. Insets show increased magnification of equivalent fields in each image to show detailed plasma membrane localization of E-cadherin in both PdxCre^late ß-cat^active and PdxCre^early ß-cat^active mutants. Scale bars: 100 µm. (M-O) Staining for glucagon (green), insulin (red) and the nuclear marker DAPI (blue), reveals islet structure in the PdxCre^late ß-cat^active mutant (N) that is equivalent to control (M). By contrast, insulin⁺ and glucagon ⁺ cells are scattered within the walls of the cysts and surrounding mesenchyme in the PdxCre^early ß-cat^active mutant tissue (O). Scale bars: 100 µm.