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  • Title: [The ultrastructure and argentophilic properties of the nucleolus organizer and centromeric regions of the chromosomes in early mouse embryogenesis].
    Author: Zatsepina OV, Severova EL, Dyban AP, Chentsov IuS.
    Journal: Tsitologiia; 1989 Jun; 31(6):626-32. PubMed ID: 2815330.
    Abstract:
    The Ag-staining of metaphase chromosomes in one-cell mouse embryos shows that the nucleolus organizer regions (NORs) are Ag-negative, whereas centromeric regions (CRs) are Ag-positive. Starting from 8-16-cell embryos, NORs stained by AgNO3 constantly, CRs remaining argentophobic. On the ultrathin sections of multicell embryos, Ag(+)-NORs differ from the chromosomal arms: they consist of loosely filaments about 6-8 nm in diameter, characterized by a low electron density. On the contrary, at one-cell stage Ag(-)-NORs are not morphologically identified: chromosomal bodies consist of uniform DNP-fibrils about 20 nm in diameter. These data permit to suppose that extended rDNA may form supranucleosomal and nucleosomal DNP-fibrils in the absence of Ag-proteins. The Ag(+)- and Ag(-)-CRs contain 10-20 nm DNP-fibrils mainly, although their density at multicell stages is higher than in one-cell mouse embryos.
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