Protocol
Methenamine Silver
for Reducing Substances
Materials
- Yellow gold chloride, 0.2% aqu.
- Sodium thiosulfate, 3% aqu.
- Stock Methenamine silver
Material Amount Methenamine, 3% aqu. 100 mL Silver nitrate, 5% aqu. 5 mL Shake until the precipitate redissolves. Silvering of the container indicates deterioration.
- Working Methenamine silver
Material Amount Stock Methenamine silver 50 mL Borax, 5% aqu. 5 mL Make just before use and preheat to 56°C.
- Mallory bleach
Material Amount Potassium permanganate, 1% aqu. 47.5 mL Sulfuric acid, 3% aqu. 2.5 mL
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.
Protocol
- Bring sections to water via xylene and ethanol.
- Optionally, remove melanin with the Mallory bleach.
- Bleach in Oxalic acid for a few minutes.
- Rinse with distilled water.
- Treat with methenamine silver solution at 56°C. until impregnated
- Wash with distilled water.
- Tone in gold chloride solution for 1 minute.
- Rinse with distilled water.
- Fix in sodium thiosulfate for 5 minutes.
- Wash well with running tap water.
- Counterstain with neutral red for 1 minute
- Rinse with tap water.
- 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.
References
- Histology Bench Manual.
Prince George Regional Hospital
