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During pancreas development, the cells of both endocrine and exocrine tissues originate from the ductal cells, indicating the existence of pancreatic stem/progenitor cells in duct cell lining in embryonic pancreas. Such a dynamic growth almost brings to an end after birth, thus the source of new pancreatic tissue is not clear and some controversy exists over whether adult pancreatic stem cells do exist in pancreas following birth and into adulthood. However, many investigators believe that the promising source of pancreatic progenitor cells lies in the cells lining the pancreatic ducts. Stem cell activity can be recapitulated in adult pancreas? Although it still remains in question, many researchers showed tissue regeneration mimicking embryonic development of pancreas by several experimental manipulations. It may imply the restoration or revitalization of stem cells under certain biological conditions. Regenerative process via the differentiation of stem/progenitor cells in adult pancreata is called neogenesis. The formation of new tissue via neogenesis was demonstrated in different models of pancreatic injuries including partial pancreatectomy, duct obstruction ligation and streptozotocin insults (Finegood et al, 1999; Sharma et al, 1999; Bonner-Weir et al, 1983). Those injuries lead to the neogenic regeneration of new islets from cells residing in the linings of duct epithelia (Kim et al, 1983; Plachot et al, 2001; Xu et al, 1999).
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