Figure 1. Chromatid-type aberrations observed in metaphases 2 hours after exposure to γ-irradiation. (A) Metaphase chromosome spread prepared from iPS12 cells irradiated at dose of 1 Gy during late G2 stage. Gray triangles indicate chromatid breaks and gray arrow indicates chromatid exchange. (B) Magnified images of chromosomes with chromatid breaks. (C) Magnified images of chromatid exchanges. 1.2 exchange of chromatid segments between different chromosomes; 3 exchange of chromatid segments between arms within chromosome; 4 exchange resulting from fusion of broken ends of chromatids within one arm of chromosome; 5 non-terminal deletions of chromatid segment with fusion of broken ends of chromatid.