Fig. 1.

A schematic representation of potential sources for beta cell proliferation and neogenesis. Accumulating data now suggest that in the early embryonic pancreas glucagon or GLP-1 directly influence progenitor cells to become endocrine cells. Alpha cells have now been shown to be a source for beta cells regeneration following an extreme loss of beta cells, where alpha cells transdifferentiate to become functional beta cells, and maintain blood glucose in mice. In most other scenarios, where the loss of beta cells is only partial, the recovery seems to be through the proliferation of existing beta cells. However, some studies have shown that ductal cells are the source of regenerating beta cells following partial loss of beta cells. New findings show that growth factors, insulinotrophic factors, or a combination of beta cell specific transcription factors can convert progenitor cells or differentiated cells within the pancreas into insulin-producing cells