title: Nucleolar activity in differentiated cells after stimulation.
abstract: Initiation of nucleolar organizer region (NOR) activity was observed by using the silver staining method at various times after activation or stimulation of differentiated cells. Two methods were used: (1) activation of human lymphocytes by treatment with phytohemagglutinin (PHA), and (2) cell-cell fusion of chick erythrocytes with squirrel monkey cells. An increase in NOR activity in lymphocytes was seen as early as 4 h after PHA treatment and between 10 and 22 h in the chick erythrocytes after fusion. In both systems, as the size of the dormant cell nucleus increased, the amount of silver staining increased until the silver-stained area approached that of cycling cells.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002459:Cell Fusion; D002642:Chick Embryo; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D000882:Haplorhini; D006801:Humans; D006822:Hybrid Cells / Q000378:metabolism; D008213:Lymphocyte Activation; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D012453:Saimiri; D012834:Silver; D013194:Staining and Labeling; D013601:T-Lymphocytes / Q000378:metabolism; D013997:Time Factors
chemical_list: D012834:Silver