Direct and Abscopal Effects of X-radiation on the Thymus of the Weanling Rat

Abstract

Summary(1) As judged by changes in weight and DNA-content, the effects on the thymus of 50 r whole-body irradiation and of 50 r to the anterior half of the body were indistinguishable. This direct effect of radiation was not altered by adrenalectomy and was recovered from in five days.(2) Using the same criteria of effect, an abscopal effect on the thymus was demonstrated after 500 r to the posterior half of the body. The abscopal effect was at its greatest five days after irradiation and appeared to be due solely to a reduction in food-intake, since it could be almost exactly imitated by simple restriction of food-intake to the same level as that caused by the irradiation.(3) There was a curvilinear relation between thymic weight and body-weight. Adrenalectomy and food restriction altered this relation in opposite directions.