Pancreas. Coloured scanning electron micrograph (SEM) of acinar (exocrine) pancreatic cells from a human normal pancreas. Acinar cells produce and excrete digestive enzymes to the small intestine, via the pancreatic ducts (center). The enzymes are excreted in vesicles known as zymogen granules. The enzymes are activated in the small intestine and aid the breakdown of carbohydrates, fats and proteins. The proteins are produced, packaged and secreted by the cells endoplasmic reticulum (highlighted) and Golgi apparatus. Connective tissue surrounds the acinus. Specimen courtesy of Mark Atkinson and Irina Kusmartseva University of Florida College of Medicine. Magnification: x3500 when printed 10 centimetres wide