Nucleolar organizing regions of normal Chinese hamster and CHW cell line chromosomes

The chromosome preparations from fibroblasts of normal male and female Chinese hamsters and the cell line CHW were stained with AgNO3. The silver stain was usually localized at the telomeres of autosomes. The marker chromosome M1 in the CHW cell line has Ag-NOR near the centre of the long arm, which indicates that either the long arms of two number 5 chromosomes fused at the telomeres or the intact telomeric region of one chromosome fused with one with a deleted telomere. The variation of Ag-NORs' number per cell and Ag-heteromorphism in chromosome number 4 were observed. The Ag-NORs of chromosome number 4 and 5 are in approximately the same position as the positive C-bands and these may play a role in the preservation of heterochromatin.