Fig. 2. Detection of a male fumarylacetoacetate hydrolase (Fah)-expressing hepatocyte after transplantation of female GMP (granulocyte/macrophage progenitors) into a male Fah^-/- mouse. The presence of donor-specific Fah protein (red, left panel) and host-derived Y chromosome signals (pink, right panel) in the same cell indicate that this trinucleated hepatocyte originates from fusion with a transplanted female (X chromosomes are stained green) myelomonocytic cell. Sequential Fah immunocytochemistry and X/Y FISH were provided by Holger Willenbring and Yassmine Akkari (Department of Molecular and Medical Genetics, Oregon Health and Science University).