Elimination of mesenchymal Wnt signaling impairs pancreas formation.

Pancreatic tissues from Nkx3.2-Cre;βcatf/f and non-transgenic (non-tg) littermates were analyzed at indicated time points. (A) Gross morphology shows smaller transgenic pancreas (right) with aberrant branching morphology. (B) Reduced pancreatic mass in e15.5 and e18.5 mutant embryos (black bars) as compared to non-transgenic littermates (non-tg, gray bars). For clarity, pancreatic mass in control mice was set to 100%. n = 5. (C,D) Histological analysis of pancreatic sections stained with H&E reveals abnormal tissue morphology in e18.5 mutant embryos (D) when compared to control (C). (E,F) Amylase+ (green) acinar cells and Mucin1+ (red) duct cells can be found in mutant pancreata at e18.5 (F). (G,H) Endocrine cells are present and express mature markers in e18.5 mutant pancreata (H), similar to control (G). Tissues were stained with antibodies against Insulin (green), Glucagon (red), and Somatostatin (blue). (I) Reduced β-cell mass (quantification described in Figure 5) in e18.5 mutant pancreata (black bar) as compared to control (gray bar). n = 3. (J) Reduced Acinar cell mass (quantification described in Figure 5) in mutant pancreata at e18.5 (black bar) as compared to non-transgenic littermates (gray bar). n = 3. (K) The ratio between β- and acinar cell areas (as described in Figure 5) at e18.5 is maintained in mutant pancreata (black bar) when compared to non-transgenic littermates (gray bar, set to “1”). n = 3. (L) Decreased proliferation of Cpa1+ precursor cells in mutant pancreata at e13.5. Bar diagram shows the percentage of pHH3+Cpa1+ cells out of the whole Cpa1+ population in mutants (black bar) and non-transgenic pancreata (gray bar). n = 3. (M,N) e13.5 pancreatic tissue stained with E-Cadherin (red) and counter-stained with DAPI (blue) shows absence of E-Cadherin mesenchymal cells in mutant tissues (N). Inserts represent higher magnification of the areas marked with white frames. p values: *p<0.05, **p<0.01, ***p<0.005.