Nucleolar organizer regions were visualised in 50 transitional cell carcinomas by using the silver staining technique. The area occupied by the individual Ag-NOR dots and other structural features related to Ag-NORs were measured by image analyzer (IBAS 2) at a total magnification of x9500. The mean Ag-NOR area ranged between 0.37-0.53 mum2 and the mean Ag-NOR area was 0.47 mum2. The Ag-NOR area or other structural features were not related to clinical stage, WHO grade, papillary status, DNA ploidy, S-phase fraction, volume corrected mitotic index or Ag-NOR count. The Ag-NOR area had no prognostic value in terms of progression or survival. The results indicate that the area of individual Ag-NOR dots is relatively constant in transitional cell bladder cancer and the enumeration of the Ag-NORs has prognostic value. In case the Ag-NORs are packed together, the Ag-NOR area reflects the number of individual Ag-NOR dots and may have prognostic value on that basis.

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