Light micrograph of a pancreatic islet. An islet (pale circular structure filling centre of image) is a group of cells in the pancreas that secretes hormones, including insulin, into the bloodstream. The islet is surrounded by pancreatic exocrine cells (darker purple and pink cells in the image) which secrete enzymes into the intestines. Haematoxylin and eosin stained tissue section. Magnification: 400x when printed at 10cm.