Pancreatic exocrine duct cells give rise to insulin-producing beta cells during embryogenesis but not after birth: shared first authorship

A longstanding unsettled question is whether pancreatic beta cells originate from exocrine duct cells. We have now used genetic labelling to fate map embryonic and adult pancreatic duct cells. we Show that Hnf1b+ cells of the trunk compartment of the early branching pancreas are precursors of acinar, duct and endocrine lineages. Hnf1b+ cells subsequent form the embryonic duct epithelium, which gives rise to both ductal and endocrine lineages, but not to acinar cells. By the end of gestation, the fate of Hnf1b+ duct cells is further restrained. We provide compelling evidence that the ductal epithelium does not make a significant contribution to acinar or endocrine cells during neonatal growth, during a 6-month observation period, or during beta cell growth triggered by ligation of the pancreatic duct or by cell-specific ablation with alloxan followed by EGF/gastrin treatment. Thus, once the ductal epithelium differentiates it has a restricted plasticity, even under regenerative settings.