Figure 9. The number of total cortical nuclei in lenses from unirradiated control mice and mice irradiated at 3 months of age. Panel A depicts the number of total retained nuclear fragments in the whole cortex, and panel B shows the number of nuclei in the cortex beneath the Central Zone only. Control and X-irradiated mice lenses were fixed, sectioned, and stained with DAPI for DNA as described in the Methods. The total number of nuclear fragments was counted in 5–7 lenses from each age and/or radiation group except the 3 month-old X-irradiated group, which consisted of data from two animals. The number of total number of cortical nuclear fragments was not significantly greater in X-irradiated lenses than controls of the same age. However, the number of nuclear fragments found in inappropriate positions below the central zone of X-irradiated lenses (panel B) was significantly higher than age matched controls at 12 months X-rayed (p<0.01), and 14 months X-rayed (p<0.005). Original magnification was 100×. The p values were determined by a 1-tailed Mann–Whitney test.