Objective To explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration.Methods Human embryonic pancreatic tissue at 7-14 weeks of gestation was collected.Diabetes mellitus rat model was induced with 65 mg/kg of streptozotocin.Insulin

glucagon

somatostatin

nestin

and cytokeratin 19 （CK19） of pancreatic tissues were observed by immunohistochemistry.Results At 9 weeks of gestation

pancreatic epithelial cells began to co-express insulin

glucagon

somatostatin

and CK19 before migration.Islet cells gradually congregated along with the increase of aging

and at 14 weeks of gestation histological examination showed islet formation.At 12 weeks of gestation

nestin-positive cells could be seen in the pancreatic mesenchyme.During early embryogenesis

islet cells of pancreatic ducts co-expressed insulin

glucagon

and somatostatin.During pancreatic regeneration after damage

nestin expression of islet cells increased.Conclusion In the early stage of embryogenesis

islet cells of primary pancreatic ducts can be differentiated to multipotential endocrine cells before migration.During tissue regeneration

pancreatic stem cells may differentiate and proliferate to form pancreatic islet.