Injured pancreatic tissue, for example, after duct ligation, undergoes remodeling, which involves the replacement of exocrine acini by duct-like structures. This acinoductal metaplasia is probably at least partly due to transdifferentiation of amylase-positive, cytokeratin-20 (CK20)-negative acinar cells into amylase-negative, CK20-positive duct-like cells. Due to the kinetics of these phenotypic changes, however, it has not been possible to demonstrate transitional stages of differentiation, which would express both markers at the same time. We took advantage of the fact that dexamethasone treatment inhibits the loss of amylase from acinar cells to demonstrate transitional cells co-expressing amylase and CK20. This was found both in vivo, where duct-ligation induced metaplasia, and in vitro, after isolation of acini. In addition, we found evidence for an acinar-to-islet conversion under the form of transitional cells co-expressing amylase and insulin. These observations strengthen the notion that fully differentiated cells, such as exocrine pancreatic cells, retain the capacity to undergo important phenotypic switches. This finding could have applications in tissue engineering or cell replacement strategies.