Microchimeric cells found in female and male samples. Red-dUTP and Green-dUTP (Abbott Molecular, USA) were used as fluorophores for the Y and X probes, respectively. FISH analysis on female lungs and male liver using probes for the X (green signal) and Y (red signal) chromosomes. Cell nuclei were counterstained with DAPI (blue). Arrows indicate microchimeric cells. FISH images of male and female cells were recorded using a Zeiss Axioplan 2 fluorescence microscope, a high-sensitivity integrated CCD camera and dedicated software (ISIS, MetaSystems, Germany).