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Methenamine Silver for Reducing Substances


Methenamine Silver

for Reducing Substances



  • Yellow gold chloride, 0.2% aqu.
  • Sodium thiosulfate, 3% aqu.
  • Stock Methenamine silver
    Methenamine, 3% aqu.100mL
    Silver nitrate, 5% aqu.5mL

    Shake until the precipitate redissolves. Silvering of the container indicates deterioration.

  • Working Methenamine silver
    Stock Methenamine silver50mL
    Borax, 5% aqu.5mL

    Make just before use and preheat to 56°C.

  • Mallory bleach
    Potassium permanganate, 1% aqu.47.5mL
    Sulfuric acid, 3% aqu.2.5mL

Tissue Sample

5µ paraffin sections of neutral buffered formalin fixed tissue are suitable. Other fixatives are likely to be satisfactory. A section adhesive is recommended.


  1. Bring sections to water via xylene and ethanol.
  2. Optionally, remove melanin with the Mallory bleach.
  3. Bleach in Oxalic acid for a few minutes.
  4. Rinse with distilled water.
  5. Treat with methenamine silver solution at 56&degC. until impregnated
  6. Wash with distilled water.
  7. Tone in gold chloride solution for 1 minute.
  8. Rinse with distilled water.
  9. Fix in sodium thiosulfate for 5 minutes.
  10. Wash well with running tap water.
  11. Counterstain with neutral red for 1 minute
  12. Rinse with tap water.
  13. Dehydrate with ethanol, clear with xylene and mount with a resinous medium.

Expected Results

  • Melanin (unbleached) – Black
  • Melanin (bleached) – Unstained
  • Enterochromaffin – Black
  • Lipofuscin – Black
  • Nuclei – Red

Safety Note

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.


  1. Histology Bench Manual.
    Prince George Regional Hospital