Caption

Illustration of an islet of Langerhans, a group of specialised cells that forms the endocrine component of the human pancreas. About one million islets are scattered throughout the pancreas. Some 3,000 cells in each islet secrete a variety of hormones. The most numerous are the insulin- producing (beta) cells (with blue cytoplasmic bodies) which secrete the hormone directly into the bloodstream. Insulin's main role is in controlling the transport of glucose; insulin deficiency results in diabetes. Other hormones secreted by other cells in the islet include glucagon, pancreatic polypeptide, and somatostatin.