In silver staining for reticulin, ferric ammonium sulfate serves as which component?

• A. Sensitizer
• B. Stain
• C. Mordant
• D. Reducing Agent

Answer: (A)

In silver staining for reticulin, the key step is making the tissue receptive to silver deposition, so the chemical that serves as a sensitizer is ferric ammonium sulfate. This iron(III) salt interacts with reticular fibers to create sites that readily attract and deposit silver ions when the developing agent is applied. It doesn’t itself provide the color (that comes from the silver stain) and it isn’t the reducing agent that turns silver ions into metallic silver, nor is it the mordant that fixes the stain to tissue. Its role is to prepare and mark the fibers so they selectively take up silver during development, giving the reticulin network its characteristic dark appearance.