Acute brain damage induced by low dosage x‐irradiation

Rats which received limited head x irradiation between 500 and 10,000 r demonstrated, within one week following exposure, a decrease in activity, anorexia, and weight loss. Routine histologic analysis of neurons revealed significant alterations only in the granule cells of the cerebellum. These cells demonstrated increasing pyknosis and shrinkage with increasing doses. A preliminary examination indicated that this alteration is reversible. Special histologic methods for glia revealed acute swelling of oligodendroglia ieading apparently to necrosis reached a maximum six to twenty-four hours after irradiation. The total numbers of altered oligodendrocytes per animal appeared directly- related to the total dosage of x ray given. Significant numbers of these cells were recorded in the brains of rats receiving as few as 150 r. Morphologic alterations are described. (auth)