Adult human HSCs generate significant numbers of hepatocytes in a noninjury fetal model. (A) Control sheep liver section (nontransplanted) stained with an antibody antihuman hepatocyte (clone OCH1E5) as described in “Materials and methods.” (B-C) Liver sections obtained at 3 weeks (B) and 4 months (C) after transplantation from sheep that received transplanted human BM CD34⁺Lin^– cells, stained with the same antibody showing a higher number of human hepatocytes in the latter (C). (D) Liver section obtained at 11 months after transplantation from sheep that received transplanted CB-derived CD34^–Lin^– cells, stained with antihuman hepatocyte antibody. Human hepatocytes in all sections can be identified by the dark brown coloration.