Wet autoclave pretreatment improves the visualization of silver-stained nucleolar organizer-region-associated proteins in routinely formalin-fixed and paraffin-embedded tissues

Mod Pathol. 1994 Dec;7(9):946-50.


This study describes the effect of wet autoclave pretreatment of routinely formalin-fixed and paraffin-embedded tissues on silver-stained nucleolar organizer-region-associated proteins (AgNORs) staining. The treatment of sections at superheated steam temperature (120 degrees C) before silver incubation leads to a significantly better discrimination of single-interphase AgNORs. Counting "black dots" both by eye and by means of a computer-aided image-analyzing system revealed considerably higher AgNOR mean numbers per nucleus in all pretreated cases when compared with the respective untreated controls. However, mean AgNOR numbers increased after autoclave pretreatment in a nonlinear manner (pairwise comparison by means of Spearman's Rank correlation coefficient: rho = 0.5), whereas measurement of the AgNOR area was less influenced by autoclave pretreatment (rho = 0.8). It is concluded that wet autoclave pretreatment of routinely formalin-fixed and paraffin-embedded archival material should be applied before AgNOR staining, particularly when quantitation of AgNORs involves counting procedures.

MeSH terms

  • Adenocarcinoma / pathology
  • Breast Neoplasms / pathology
  • Carcinoma, Squamous Cell / pathology
  • Colonic Neoplasms / pathology
  • Formaldehyde
  • Histocytological Preparation Techniques*
  • Humans
  • Mouth Neoplasms / pathology
  • Nuclear Proteins / analysis*
  • Nucleolus Organizer Region / chemistry*
  • Paraffin Embedding
  • Silver Staining*
  • Tissue Fixation*


  • Nuclear Proteins
  • Formaldehyde