['To investigate influencing factors of β-cells differentiation and microenvironment in embryonic development and regeneration, in order to conduct therapeutic efforts to broaden β-cells mass in diabetes.', 'The expression of Ngn3 (Neurogenin-3) and microenvironment of β-cells differentiation during embryonic pancreas development at 4-12 weeks of gestation and regeneration after pancreatic islet injure observed by immunohistochemical staining.', 'The results showed that the expression of Ngn3 not only in pancreas development but also in β-cells regeneration in rat diabetic model (DM) by streptozotocin (STZ) treatment. Pancreatic mesenchymal tissue always accompanied by islet cells differentiation and there is a short expression of Ngn3 occurrence before all islet cell types differentiated from pancreatic epithelium. The expression of Ngn3 including ectopic expression also appearance in β-cells injured rat pancreas. In addition, there are some Nestin-positive cells where located in pancreatic duct, islets and mesenchyme were detected in DM. Double immunostaining witness Brdu/Ngn3-positive cells was only in pancreatic mesenchyme after β-cells injure.'] Is short-reactivation of neurogenin-3 and mesenchymal microenvironment require for β-cells differentiation during fetal pancreas development and islet regeneration?