Fig. 2. Analysis of early pancreatic development in mutant embryos. (A-C) Pancreatic development of the respective mutant embryos at E13.5 as determined by PDX1 immunofluorescence (green). (E-G) Immunofluorescence for PDX1 (green) and HES1 (red) in pancreatic dorsal buds of mutant embryos at E12.5. (H-J) Double staining of pancreatic dorsal buds of mutant embryos for X-gal (blue) and glucagon (brown) at E11.5. (K-M) Nuclear expression of NGN3 in E13.5 mutant pancreata by immunohistochemistry. Arrowheads mark the areas in insets (enlarged 4x). Arrows in insets mark NGN3⁺ cells (black). (O-Q) Insulin expression in mutant pancreata at E13.5 by immunofluorescence (red, arrows). (S-U) Double-immunostaining for phospho-histone H3 (PHH3, black, arrows) and PDX1 (brown) at E13.5. (D,N,R,V) Quantification of the number of NGN3⁺, Insulin⁺ and PHH3⁺ cells, and size of area of PDX1⁺ cells, in buds of E13.5 Rbpj^+/-;R26R, Notch1/2KO;R26R and RbpjKO;R26R embryos. Histograms show the mean size±s.d. for ventral and dorsal buds of three embryos each. Nuclei were counterstained with DAPI. Gluc, glucagon; vb, ventral bud; db, dorsal bud. Scale bar: 50 µm.