Glucagon-expressing α-cells are more severely reduce in the paired domain mutant mouse line Pax6Aey18than in Pax6Sey-Neuhomozygotes. A-I. Immunstaining of pancreatic sections of e18.5 wt and mutant embryos. Glucagon+ α-cells are nearly absent from the pancreas of paired domain mutant embryos (Pax6Aey18; 0-4 weakly positive cells/section; ≤1% of wt) but are present at 25% of wt in Pax6Sey-Neu transactivation domain mutants. β-cells are reduced and islets are disorganized in both mutant lines. The proportion of somatostatin+ δ-cells is visually unchanged in both mutants but PP cells are reduced in Pax6Aey18. J-K. Quantification of relative β-cell and α-cell area in wt and mutant e18.5 embryos. Individual cell sizes were comparable. (error bars = SD; 3-5 mice/group; * p < 0.05).