Comparative study of lesions in the brain of rats exposed to heavy ions: accelerator and stratospheric flight research.

Irradiations of rat's brain with heavy ionized particles (12/6C, 291 Mev/nucleon, 100 to 300 ions/mm2) have been carried out at the Lawrence Berkeley Laboratory. Exposures were made with slowed ions which stopped within the brain as well as with more energetic particles which passed through. Histological examination of irradiated encephalons by optical microscopy showed zones of glial reaction and an increased number of darkly staining cells. By electron microscopy, intercellular edema, various alterations of nervous cells and macrophagy were observed, especially with stopped ions.