We recently developed a novel rat model for liver repopulation, heterografting of microliver slices, aimed at overcoming the limitations inherent in both whole liver and hepatocyte transplantations. The aim of the present study was to evaluate the potential of whole fetal liver transplantations to survive and differentiate within the adult liver, using the adult liver slice transplantation model. Embryonic day 14 whole fetal livers from dipeptidyl peptidase IV؉/؉ wild-type Fischer 344 rats were transplanted into the livers of dipeptidyl peptidase IV؊/؊ mutant rats. Adult hepatic markers, dipeptidyl peptidase IV, albumin, glycogen, and proliferation cell nuclear antigen-proliferation cell nuclear antigen (PCNA) were assessed in the transplanted liver tissue by immunohistochemistry. Two groups of 9 rats each were transplanted with 3 fetal livers per recipient. Two months later the rats were sacrificed and the markers were detected in the transplanted tissues. In conclusion, the results of this study raise the possibility that fetal liver transplantation could serve as a model for genetic metabolic liver diseases. (