Explanation

The ‘islets of Langerhans’ are the clusters of cells of the endocrine portion of pancreas. These contain four types of cells (i) Alpha cells (32-38%) secreting glucagon (ii) Beta cells (60-70%) secreting insulin, (iii) Delta cells secreting somatostatin and (iv) F-cells secreting pancreatic polypeptide hormone to control somatostatin.