Fluorescence in situ hybridization (FISH) analysis of the infant's tumor tissue (a resected sample) and microsatellite analysis. (A) FISH analysis with probes for X (red) and Y (green) chromosomes showed the chimeric pattern; XX in tumor tissue and XY in normal tissue. Image acquisition information: Olympus BX-51 microscope; UPlanApo 100×/1.35 oil objective; DAPI nuclear stain; Nikon DXM1200 camera. (B) Microsatellite analysis on chromosome 3 was carried out using DNA samples extracted from (1) the father's peripheral blood, (2) the mother's bone marrow film, (3) the infant's peripheral blood, and (4) the infant's tumor tissue (a resected sample). The resected tumor tissue had 3 peaks and the right one (arrow) was the noninherited maternal DNA marker. Analysis of the peak height indicated that 55% of the resected tissue was of maternal origin.