Grocotts Methenamine Silver stain Flashcards
What is GMS?
A silver impregnation stain used to detect fungal cell walls (rich in polysaccharides)
GMS stands for Gomori’s methenamine silver stain, which is commonly used in histology.
What is the role of methenamine silver in staining?
Reacts with fungal carbohydrates, reducing silver ions to metallic silver, which appears black
This process highlights fungal structures in tissue samples.
True or False: Argentaffin silver stain requires a reducer.
False
Argentaffin stains do not require a reducer to visualize certain cells.
What does chromic acid do in the staining process?
Oxidizes polysaccharides in fungal cell walls, exposing aldehyde groups
This enhances silver binding sites on fungal structures.
How do methenamine silver ions bind to fungal components?
They react with aldehyde groups
This selective binding is crucial for the visualization of fungi.
What is the function of gold chloride in the staining process?
Enhances contrast by replacing + aggregation of gold ions
This helps in better visualization of the stained structures.
What is the purpose of sodium thiosulphate in the staining protocol?
Removes any unbound ions during the fixing step
This step is essential to ensure clarity in staining.
What is the role of light green in staining?
Product contrast
It helps differentiate between stained structures.
What reduces silver ions?
Reaction between aldehydes on polysaccharides of fungal cell wall and silver ions results in their reduction producing a visible metallic silver which is brown/black in colour.
What are the components of GMS stain? (5)
- Chromic acid
- Silver stain
- Gold chloride
- Sodium thiosulphate
- Light green
