Light microscopy of pancreatic exocrine cells forming glandular clusters. These cells which make up around 95% of the pancreas, secrete digestive enzymes that are exported to the dudoneum via a pancreatic duct system. Typical of protein-secreting cells, they have prominent nuclei, show masses of rough endoplasmic reticulum (blue-purple) and enormous quantities of zymogen granules (pink) which store the enzymes in inactive forms. Magnification x400 when printed at 10 cm.