Studies on Thymus of the Mammal. IX. Histochemical Study of Irradiated Mouse Thymus.

Abstract

The thymus of BAlb/c male mice, 30-40 days old was removed from control animals and from mice 2, 4, 8, 12, 24, 36 hours and 3, 5, 7 and 9 days after exposure to sublethal irradiation. Gomori''s lead sulfide method was used to demonstrate the sites of acid phosphatase activity; frozen sections colored in oil red O were studied for the presence of lipids. In the normal thymus relatively few mesenchymal reticular cells gave a positive reaction for acid phosphatase. As early as 2 hours after irradiation they mobilize to become active macrophages which stain deeply in the acid phosphatase technique. The macrophages become more numerous until at 24 and 36 hours after irradiation the involuted cortex is full of cells laden with lipids and positive for acid phosphatase. At 3, 5 and 7 days there is a gradual diminution in number and size of reactive cells. At 9 days the thymus appears essentially normal.