Comparison of silver staining of nucleolus organizer regions in human lymphocytes and fibroblasts.

Ag-staining of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding in repeated lymphocyte and skin fibroblast cultures from three different individuals. A similar pattern of Ag-stainability of NORs was found in the two tissues in each individual. Small differences concerning, in each case, only one of the acrocentric chromosomes were found between repeated lymphocyte cultures, as well as between lymphocyte and fibroblast cultures of the same individual without indication of any prevalence of one tissue type in a certain direction. The possibility that these differences are caused by different stages of NOR activation is discussed.