Light and electron microscopy of mouse lymphosarcoma LS/BL cells during the first hour after irradiation with x-rays

Mouse lymphosarcoma LS/BL cells growing in tissue culture were irradiated with 100, 316 and 1000 R and fixed 5, 15 or 60 minutes later. Semi-thin sections were studied with an optical and ultra-thin sections with an electron microscope. Differences between the morphology of individual nuclei were found with the light microscope in all groups, including controls; the rate of their occurrence was without any relation to irradiation. They may reflect the differences in the state of LS/BL cells which were not completely adapted to cultivation in small glass tubes. On the other hand, the frequency of some ultrastructural changes seen with the electron microscope showed a relation to the irradiation. These were: undulation of the outer nuclear membrane and dilatation of the space between the outer and inner nuclear membranes, slots in karyosomes adjacent to the surface of the nuclei, enlargement of cisternae and vesicles of endoplasmic reticulum and Golgi apparatus. The importance of careful examination of control groups in such experiments is stressed. (author)