Long-term neuropathological consequences of low-dose X-irradiation on the developing rat cerebellum.

Inbred F344/DuCrj male rats aged 0, 3, 6, 10, 13 and 17 days were exposed to single whole-body X-irradiation at doses of 25, 50 or 100 rad. They were sacrificed at 8 weeks of age for gross and microscopic examinations of the cerebellum. For a quantitative analysis of the cerebellar development, cells in the molecular layer of the declive were counted in 2μm-thick mid-sagittal sections of the vermin, and the population of cells per 1 mm2 of the section was estimated. A significant reduction in cell population was found only in rats exposed to 100 rad at 6 days of age. No significant difference between control and irradiated animals could be detected in the weight of the body, brain, or cerebellum. Neither gross malformation nor abnormality of the cortical architecture of the cerebellum was observed.