Which reagent is used as the sensitizer in the Steiner procedure?

• A. Uranyl Nitrate
• B. Silver Nitrate
• C. Gum Mastic
• D. Absolute alcohol

Answer: (A)

The main idea is that Steiner’s reticulin stain requires a sensitization step to prepare the tissue for silver deposition. Uranyl nitrate provides the sensitizer. The uranyl ions bind to tissue elements, creating sites that readily attract and reduce silver in the subsequent impregnation/ development steps. This makes the reticular fibers appear prominently (typically dark) against a lighter background.

The other reagents don’t serve this role: silver nitrate supplies the silver for impregnation, but it isn’t the sensitizer; gum mastic isn’t part of the staining chemistry and is not used to sensitize tissue; absolute alcohol is just a dehydrating solvent and does not sensitize tissue for silver deposition.