Immunolocalization of pancreatic hormones and pancreatic polypeptide and PYY in catshark pancreas. (A) The distribution of the pancreatic hormones insulin (blue), glucagon (green) and somatostatin (Red) in uniquely shaped islet structures. (B) Pancreatic polypeptide (red) specific antisera fail to stain a specific subset of endocrine cells in the pancreas, while insulin (blue) and glucagon show a normal distribution. (C-D) PYY shows colocalization with most of the insulin immunoreactive cells but not glucagon or somatostatin (E-F). All images are 250x magnification.