[Characteristics of non-nucleolar RNP structures in hepatocyte nuclei in the early stages of the stimulation of proliferation].

Quantitative changes of extranucleolar RNP-structures were studied on ultrathin cell sections of hepatocytes in the first hours after partial hepatectomy of guinea pigs. This purpose in mind, the sections were treated according to Bernhard. In 2.5 hours after the operation, the relation quantity of perichromatin and interchromatin fibrils increased, whereas the number of perichromatin and interchromatin granules decreased. Therefore the early response of hepatocytes to the proliferative stimulus represents not only intensification of the synthesis of a newly formed hnRNA but also enhancement of the processing and transport of this RNA. After 5 hours the relative quantity of both types of RNP-fibrils diminished to the control level, while the number of perichromatin granules was even smaller than that in the previous case. This points out that the transcription of the extranucleolar RNA becomes less active, and the processing and transport of the earlier synthetized RNA continues. Within the next time lapse (9 hours) the relative quantity of all the studied RNP-structures was low, the content of perichromatin granules being dramatically decreased as compared to that after 5 hours. A comparison of changes in RNP-structures with the degree of condensation of chromatin allows a conclusion that the decondensation of some part of condensed chromatin after 2.5 and 9 hours is functionally different. If initially it is required for the intensification of the template synthesis, thereafter it may be connected with the preparation for replication.