SILVER STAINED NUCLEAR ORGANIZER REGIONS (AgNORs) - PREDICTORS OF INCIPIENT CELLULAR ALTERATIONS - A REVIEW

Nucleolar Organizing Regions (NORs) are the loops of ribosomal DNA, which occur in the nuclei of cells possessing the genes for synthesizing rRNA. These regions (NORs) have been assigned the name ‘fibrillar centers’ (fcs) at the ultrastructural level and these should be regarded as the true interphase counterpart of the NORs present on the five human acrocentric chromosomes i.e. chromosome number 13, 14, 15, 21 and 22. Silver staining Nucleolar Organizer Regions (AgNORs) have been attracting much attention because of claims that their frequency within the nucleus has been significantly higher in malignant cells than in normal, and that they produce a very useful means for examination of nucleolar structures and variations in nucleolar activity. 
Keywords: Chromosomes, Nucleolar Organizing Regions, Silver staining.