ABSTRACT
A fundamental problem in pancreas biology concerns the cellular origins of adult pancreatic β cells. Identifying the cells that give rise to new β cells will have important implications for the design of future regenerative therapies for diabetes. Numerous studies have suggested that β cells are generated in vivo from a pool of stem or progenitor cells residing in pancreatic ducts, inside islets or in the bone marrow. More recent experiments have challenged this model, and indicated that new adult β cells derive m ainly by self-proliferation of existing, terminally differentiated β cells. In this chapter we summarize the evidence regarding the critical contribution of β-cell proliferation, and discuss some im plications of this view for the study of pancreas dynamics and diabetes.
