Pancreas tissue. Coloured scanning electron micrograph (SEM) of pancreas tissue that has been freeze-fractured to show internal details. Seen here are pancreatic ducts (large one seen at upper centre), blood vessels (red, several seen at lower centre), and acinar cells containing many zymogen granules (small round objects). The acinar cells secrete digestive enzymes for use in the small intestine. The enzymes are secreted in the zymogen granules, and passed to the small intestine through the pancreatic ducts. Magnification: x1700 when printed 10 centimetres wide.