Immunofluorescence of mouse livers (40× magnification), harvested 9 days after transplantation of GFP marked cBAL111 cells (green). Nuclei were visualized by DAPI staining (blue) (A-F, I). The majority of cells exhibited an elongated morphology (arrows); a small number of cells adapted hepatocyte morphology (arrowheads, A and B). Human origin of the cells was confirmed using an antibody against human mitochondria (red) (C and D); Human mitochondria fluorescence (C), GFP fluorescence (C insert) and merge of human mitochondria and GFP fluorescence (D, insert shows higher magnification). With hepatic differentiation, the cells lost the expression of vimentin, a marker of undifferentiated mesenchymal cells (red; insert shows single stain) (E). Hepatocytes originating from cBAL111 are undistinguishable from the surrounding murine hepatocytes in CPS expression (red) (F). No cells originating from cBAL111 were found in pericentral regions; cBAL111 in vivo did not express GS (G). Transplanted cBAL111 cells with hepatocyte morphology showed co-localization of GFP and human albumin (red) (H-J); albumin fluorescence (H), GFP fluorescence (I) and merge of albumin and GFP fluorescence (J). P, portal vein; C, central vein.