Pancreas tissue. Scanning election micrograph of a large vein in part of the exocrine pancreas (blue). Digestive enzymes are secreted in the zymogen granules, and passed to the small intestine through the pancreatic ducts. The thin walled vein (bottom)(blue grey) is filled with red blood cells. Connective tisuue is blue-grey. Magnification: x2500 when printed 10 centimetres high.