Transdifferentiation is a process in which one differentiated cell type is converted to another. A unique example of transdifferentiation is the development of hepatocytes from pancreatic cells in adult hamsters and rats. In this communication we report the induction of pancreatic hepatocytes in hamsters that were given 2, 3, 7, 8-tetrachlorodi benzo-p-dioxin (TCDD). Two or 6 intraperitoneal (ip) injections ofTCDD at a dose of 100 pg/kg bodyweight at 4-wk intervals induced pancreatic hepatocytes in 75% and 89% of the animals respectively. In animals given only two doses of TCDD each pan creas contained one to two hepatic foci, whereas when six injections were adminis tered multiple hepatic foci were observed. By hematoxylin and eosin stain and by periodic acid Schiff stain, the pancreatic hepatocytes were morphologically identical to those in normal liver. Although the exact mechanism by which TCDD induces the transformation is not clear, it is conceivable that TCDD acting through receptor-me diated mechanisms is activating the repressed liver-specificgenes in the pancreas.
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