Figure 7 Confocal microscopy analysis of liver tissue of a female rat one month after infusion of bone marrow derived cells (BMDCs) isolated from male GFP‐transgenic rats (A) (B). Tissue has been processed with fluorescent in situ hybridisation (FISH) for the Y chromosome (Cy3, red nuclear signals) and immunostained for GFP (Cy5 labelling, blue cytoplasmic stain). Nuclei are dark as there is no nuclear DAPI labelling. Clusters of GFP positive hepatocytes incorporating the Y chromosome signal are visible throughout the parenchyma (60×); interestingly there are frequently multiple Y signals in a nucleus, denoting polyploidisation, a typical hepatocyte feature. (B) An enlarged section of the area indicated by an asterisk (*) in the panel (A). (C, D) Fluorescent microscopy of control liver tissue: here DAPI (blue) is used to label the nuclei as no cytoplasmic fluorochrome is used; again Y chromosome detection is with the Cy3 labelled chromosome paint (red). (C) Male control liver shows nuclear Y chromosome labelling (red signals). (D) Female control livers have no nuclear Y chromosome labelling.