Nucleolar silver stained granules in rat Yoshida sarcoma cells after RNA synthesis inhibition.

The number of nucleolar silver stained granules representing nucleolus organizer regions in interphase nuclei was studied in Yoshida ascitic sarcoma cells without and after the inhibition of the nucleolar RNA synthesis with actinomycin D or cyclophosphamide. The results demonstrated that the number of nucleolar silver stained granules decreased after the inhibition of the nucleolar RNA synthesis with these drugs disregarding the mode of their action. In addition, the decrease of nucleolar silver stained granules in number produced by actinomycin D was dose dependent. Similarly, the number of nucleoli without silver stained granules increased depending on the dose of the administered actinomycin D.