Visualization of nucleolar organizer regions im mammalian chromosomes using silver staining

Chromosoma. 1975 Nov 20;53(1):37-50. doi: 10.1007/BF00329389.


A simple ammoniacal silver staining procedure, designated Ag-AS, differentially stains the chromosomal locations of ribosomal DNA in certain mammalian species. This was critically demonstrated by Ag-AS staining of the nucleolus organizer regions in karyotypes of the same species and cell lines used for locating the ribosomal cistrons by DNA/RNA in situ hybridization. With Ag-AS, silver stained NORs (Ag-NORs) are visualized as black spherical bodies on yellow-brown chromosome arms. Ag-NORs were visualized throughout mitosis at the secondary constrictions in the rat kangaroo, Seba's fruit bat, Indian muntjac, and Rhesus monkey. The Chinese hamster and cattle have telomeric Ag-NORs, the mouse subcentromeric Ag-NORs, and the field vole Ag-NORs as minute short arms or choromosomal satellites. Ag-NORs occur at both secondary constrictions and at telomeres in the cotton rat. Variability in Ag-NOR pattern included differences in the number of Ag-NORs per cell within a cell population, size of Ag-NORs among chromosomes of a complement, and presence of Ag-NOR on particular chromosomes in two cell lines of the Chinese hamster. The available cytochemical data suggest that the Ag-AS reaction stains chromosomal proteins at the NOR rather than the rDNA itself.

MeSH terms

  • Animals
  • Arvicolinae
  • Chiroptera
  • Chromosome Mapping*
  • Chromosomes / metabolism
  • Chromosomes / ultrastructure*
  • Cricetinae
  • Deer
  • Female
  • Genes*
  • Haplorhini
  • Karyotyping
  • Macaca mulatta
  • Macropodidae
  • Male
  • Mice
  • Mitosis
  • Nucleoproteins / analysis
  • RNA, Ribosomal / biosynthesis
  • Rats
  • Silver
  • Staining and Labeling


  • Nucleoproteins
  • RNA, Ribosomal
  • Silver