Langerhans Islet

The islets of Langerhansare endocrine cell cluster well ordered in lobules, of 0.3–0.7 mm in diameter, containing from 3,000 to 4,000 cells, and located mainly in the tail region of the pancreatic gland. Discovered in 1869, though representing only 2 % of the whole organ, they serve to coordinate the physiological control of the glycemic values in the blood. Five different hormone-secreting cell types constitute the islets’ cytoarchitecture: alpha cells producing glucagon, beta cells producing insulin and amylin, delta cells producing somatostatin, PP cells (gamma cells) producing the pancreatic polypeptide, and epsilon cells producing ghrelin. In human beings, the alpha and beta cells are in close relationship with each other. Representing nearly 90 % of the total islet cells, their secretive activity is modulated by the blood glucose levels: when low concentrations of sugar are detected, the islets respond with the glucagon secretion to induce the glucose release from the hepatic...