title: Frequency of Ag-stained nucleolus organizer regions in the acrocentric chromosomes of man.
abstract: The Ag-stainability of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding of cultured lymphocytes in 51 karyotypically normal persons (31 males and 20 females). A consistent pattern of Ag-positive NORs was found in each individual. Ninety percent of individuals have a model number of 8--10 Ag-positive NORs per cell. The frequency of Ag-positive NORs is similar in all five acrocentrics. A statistically nonsignificant lower frequency is found in chromosome 22. Ag-negative NORs on both homologues were found in four cases. The observed frequency distribution of individuals with homozygous NOR-positive, heterozygous, and homozygous negative acrocentric chromosomes was in accordance with the Hardy-Weinberg law in all five pairs of the acrocentric chromosomes as well as in total. No sex difference was observed on our material.
mesh_terms: D002466:Cell Nucleolus / Q000648:ultrastructure*; D002875:Chromosomes / Q000648:ultrastructure*; D002904:Chromosomes, Human, 21-22 and Y; D005260:Female; D006801:Humans; D008214:Lymphocytes; D008297:Male; D012737:Sex Factors; D012834:Silver; D013194:Staining and Labeling
chemical_list: D012834:Silver