Figure 2. Hybrid cardiomyocytes expressing both host (GFP) and mouse (nuclear lacZ) markers in cTnI/lacZ transgenic mouse hearts transplanted into GFP⁺ transgenic rats. A, B) Beta–galactosidase is expressed in the whole heart in cTnI/lacZ transgenic mice (A) and is specifically localized in the nuclei of cardiomyocytes (B). C–E) Confocal images of a GFP⁺ cardiomyocyte (C) expressing nuclear beta-galactosidase (D) and sarcomeric MyHC (E). F–H) A GFP⁺ cardiomyocyte (F) with nuclear beta-galactosidase (G) and the image reconstruction (H). Scale bars = 30 µm.