NUCLEAR ORGANIZER REGIONS (AGNORS) STAINING ON UNDECALCIFIED BONE EMBEDDED IN RESIN - LIGHT AND TEM METHODOLOGIES

Nuclear organizer Region (NORs) are parts of the nucleoli involved in the synthesis of ribosomes. Silver-stainable proteins of the nucleolar organizer regions (AgNORs) which are increased in neoplastic cells, c an be localized in tissues embedded in resins. The method was adapted to bone, which needs to be processed undecalcified for histomorphometr ic purposes. Sections of undecalcified biopsies embedded in methacryli c resins were extensively demineralized in EDTA. They were stained for AgNORs and conterstained with metanil yellow. Sections were flattened with polyvinyl alcohol (a hydrophilic glue), which makes them suitabl e for light microscopy. The same method was applied for transmission e lectron microscopy (TEM) by embedding undecalcified blocks in an hydro philic resin (LR-White). Ultrathin sections of bone mounted on gold gr ids could be stained for AgNORs after EDTA demineralization. The inter est of hpdrophilic resins as embedding media was evidenced for AgNORs staining.