Fig. 5. Progenitor cells engrafted and proliferated in the mouse liver. (A) In situ hybridization showing nuclear localization of the signal in fetal human liver. (B) Negative control tissue showing absence of hybridization when the probe was omitted. (C) shows transplanted cells with dark nuclear staining (arrow) in a portal area (Pa) of recipient mouse liver after 24 hours. (D and F) show integration of transplanted cells in the liver six weeks after transplantation with transplanted cells localized by in situ hybridization (arrows) and histochemistry showing either G-6-P expression (D) or bile canalicular ATPase activity (arrowheads, E). (F) Only occasional transplanted cells were observed as shown six weeks after cell transplantation. (G) shows the increased number of transplanted cells six weeks after repeated CCl₄ treatment to induce cell proliferation. Panels C, F and G were counterstained with methyl green.