Pancreatic acinus. Coloured high resolution scanning electron micrograph (SEM) of an acinus in the pancreas. An acinus is a collection of glandular epithelial cells. Coloured blue are the cell nuclei. The orange and yellow coloured circles are granules of lipolytic, glycolytic and proteolytic enzymes in their inactive forms. Under stimulation from the intestinal hormone pancreozymin the enzymes are released into ducts (not seen). When activated these enzymes will aid digestion of food in the duodenum. The cytoplasm of the acinar cells is filled with a network of densely folded endoplasmic reticulum (green).