Pancreatic cells. Coloured scanning electron micrograph (SEM) of enzyme-secreting cells in the pancreas. These exocrine cells, known as acini cells, secrete digestive enzymes into a network of ducts that feed into the duodenum (part of the small intestine) via the main pancreatic duct. The enzymes are activated on reaching the duodenum, where they aid the breakdown of carbohydrates, fats, proteins and nucleic acids. Endocrine cells located within the pancreas' exocrine tissue produce the hormones insulin and glucagon, which regulate blood glucose levels. Magnification: x350 at 6x7cm size.