Electron microscopic examination of mouse thymus lymphocytes, following gamma irradiation

The radiation-induced afterations in mouse thymus lymphocyte surface were studied. The animals were totally gamma-irradiated with single doses of 50, 100, 150, 250 and 500 r 137Cs and sacrified 24 hours later. Part of the thymus was used to make preparations for examination of scanning electron-microscope and the remaining part - for preparations for electron-microscopic examination of the glycoprotein layer of the cell membrane by the method of Luft with ruthenium red (RR) coloration. There was no difference between thymus lymphocytes of the control animals and of gamma-irradiated mice with 50 r. A rugged cell surface with several bulges and microvilli was observed after irradiation with 100 r. The RR-positive layer around the thymus lymphocytes, which do not show ultrastructural a lterations, was thin and even. After irradiation with higher doses, the thymus lymphocyte surface resumed its smoothness with some isolated pimple areas. On examination with transmission electron-microscope, however, a different thickness of the RR-positive layer around the cells was observed. After irradiation with 500 r, the thymus lymphocytes examined with a scanning electron-microscope, showed an irregular form and areas of destruction of the cell surface - a manifestation of cell degeneration. This investigation shows that after irradiation with relatively low dose (100 r), the scanning electron-microscope examination reveals alterations of the thymus lymphocytes which are more demonstrative in comparison with the cytoplasmic and nuclear alterations observed under transmission electron-microscope. After RR coloration the changes in the clycoprotein layer may be associated with the alterated type of migration and with the electrophoretic motility of the thymus lymphocytes in the organism after irradiation. (A.B.)