Fig. 3. Histological analysis of pancreatic tissue at E18.5. Hematoxylin/Eosin (A,B) and amylase (red; C,D) staining of E18.5 pancreatic tissue shows normal exocrine architecture in Hhip^–/– (Hip1 in figure; B,D). By contrast, clustering (A,B; broken yellow lines) and size of islets as shown by insulin staining (green; C,D) is impaired in Hhip^–/– embryos (B,D). Expression of smooth muscle actin is confined to blood vessels in mutants and wild type (E,F), indicating that loss of Hhip function does not lead to transformation of pancreatic mesenchyme into duodenal mesoderm.