Characterization of nucleolar organizers in carcinomatous mammmary lesions

: An argyrophil stain for nucleolar organizer regions (NORs) has been applied to paraffin sections of 24 malignant and 3 benign breast tumors. It was found that the total number of Ag-NORs in malignant breast lesions (3.66) significantly exceeded those in benign lesions (1.65). Relationship between this index and some clinical parameters was studied. A positive correlation between NORs and histological grading and prognostic was found.