[The 3-dimensional organization of the nucleolus and the nucleolus organizer regions in differentiated cells. III. Changes in the nature of the distribution of argentophilic proteins in the nucleoli of mouse hepatocytes with stimulation of the hepatocytes to proliferation].

The stereological and morphological analysis of Ag-positive zones revealed the principal difference in quantity and distribution of Ag-NOR proteins in reticulated and nucleolonemal nucleoli of mouse hepatocytes. It is shown that reticulated nucleoli of resting hepatocytes are characterized with the presence of discrete rounded Ag-positive zones, whose quantitative parameters correspond to the fibrillar centers and dense fibrillar component taken together. The analysis of the three-dimensional structure of Ag-positive zones of nucleolonemal nucleoli has revealed considerable changes in quantity and distribution of Ag-NOR proteins due to proliferative stimuli. 22 hours following operation, a continuous, strongly winding strand of nucleolonema is revealed in the nuclei. Taking into account that Ag-NOR proteins are associated with the transcriptionally active regions of rDNA it may be suggested that this structural conversion was due to decondensation and activation of inactive regions of r-chromatin. A considerable growth of Ag-positive zone volume during the conversion of reticulated nucleoli into the nucleolonemal type may be explained by the increase in Ag-NOR protein contents.