Fig. 3. Acinar cell loss and ductular hyperplasia in orpk mice. Staining for amylase indicates normal exocrine architecture in E18.5 orpk pancreatic tissue (A,B). Mucin 1 staining reveals ductal defects in orpk mice with small dilations of intracinar ducts (arrow in B). After birth (P4), extensive acinar cell loss occurs, as shown by the decrease of amylase staining in orpk mice (C,D; shown at higher magnification in E,F). Increased dilation of duct-like structures was observed after birth (P4), as shown by mucin staining (C-F). Insulin-expressing cells are present in duct-like structures of orpk mice at P9 (H, arrows). No insulin-expressing cells could be detected in ducts of wild-type mice at P9 (G).