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Grocott's Methenamine Silver (GMS) stain
For the detection of fungal elements in tissue sections. This is an essential stain and should be used whenever a fungal etiology is suspected.
Mechanism: Chromic acid treated fungi possess aldehydes which will reduce the hexamine-silver mixture to produce a black deposit, i.e. an argentaffin reaction. Fungi stain black.
Solutions.
1. 5% aqueous chromic acid
2. 1% aqueous sodium bisulphite
3. 5% aqueous borax
4. 0.1% aqueous gold chloride
5. 2% aqueous sodium thiosulphate
6. Stock Methenamine Silver solution.
Add 5 ml of 5% silver nitrate to 100 ml of 3% hexamine. A white precipitate will form which, on shaking, will dissolve. This solution will keep from 1-2 months at 4oC.