[Electron microscopy autoradiographic investigation of DNA synthesis in a nucleolus]

A compensatory increase in the number of the DNA synthezising hepatocytes was induced in mice by the CCl4 injection. Some variants of the distribution of the labeled DNA were detected in the nucleus after a short-term (20-30 min) labeling of the hepatocytes by thymidine-3H. In one of the variants the label was localized almost exclusively in the body of the nucleolus. Some features of the replication of intranucleolar DNA were noted: a rather poor labeling at this time of all the other nucleus structures including nucleolush eterochromatin, synchronism of DNA synthesis in different nucleoli of one nucleus; the decrease in electron density of the body of the nucleolus and a high label concentration above it.