Figure 1.

Different mechanisms of endogenous beta cell regeneration exist throughout life. (1) Embryonic pancreas. During embryonic development, the beta cells primarily arise from the Neurogenin3 (NEUROG3)-expressing endocrine progenitor population located in epithelial ducts through a mechanism of neogenesis. (2) Early postnatal pancreas. In the first two weeks after birth, the beta cell population expands through a combination of neogenesis and replication of existing beta cells. (3) Adult pancreas in basal conditions. In the adult, a limited number of new beta cells form through replication. (4) Adult islet in stressed conditions. Adult beta cells exposed to physiological stresses (pregnancy, obesity, insulin resistance, damage) regenerate through both neogenesis (rare) and the replication of existing beta cells. Key: beta cells (pink); epithelial ducts (blue); replicating beta cells (orange); acinar cells (yellow).