Which technique is used to visualize basement membranes by silver deposition?

• A. Methenamine silver
• B. PAS
• C. Aldehyde fuchsin
• D. Picric acid

Answer: (A)

Silver deposition to visualize basement membranes is achieved with the Gomori methenamine silver stain. This method makes basement membranes appear dark or black because silver ions are reduced and deposited on the argyrophilic components of the basement membrane. It is especially useful for clearly outlining structures like the glomerular basement membrane in kidneys, and it also highlights fungi that bind silver. Other stains rely on different chemistry: PAS uses periodic acid to oxidize carbohydrates and then Schiff reagent, yielding a magenta color without silver deposition; aldehyde fuchsin targets elastic fibers; picric acid is a general dye used in other staining schemes and does not visualize basement membranes through silver deposition.