STUDIES ON MACRONUCLEUS OF PARAMECIUM AURELIA .3. LOCALIZATION OF TRITIATED THYMIDINE BY ELECTRON MICROSCOPE AUTORADIOGRAPHY

Following specific incorporation of tritiated thymidine into the DNA of the macronucleus of Paramecium aurelia for varying periods of time the vast majority of silver grains in electron microscope autoradiographs are associated with the area containing the small bodies and matrix. At best only 5% of the silver grains overlying the macronucleus are attributable to the large bodies. This is consistent with the view that the large bodies are the nucleoli of the macronucleus. © 1969 Springer-Verlag.