Which fixatives are acceptable for Prussian Blue staining?

• A. Alcohol or 10% Neutral Buffered Formalin
• B. Bouin's fixative
• C. Glutaraldehyde
• D. Zinc fixative

Answer: (A)

Prussian Blue staining detects ferric iron in tissue, so the fixative must preserve iron in place without extracting or altering it and allow the staining reagents to reach the iron. Alcohol fixation and 10% neutral buffered formalin do this well: they preserve cellular structure and iron without removing it or masking ferric iron, allowing the blue ferric ferrocyanide reaction to develop properly.

Bouin's fixative contains picric acid, which can extract iron and interfere with the staining reaction, producing poor or unpredictable results. Glutaraldehyde creates strong cross-links that can hinder reagent penetration and mask iron, leading to weak staining. Zinc fixatives can alter metal interactions in the tissue and may interfere with the Prussian Blue reaction as well.

Therefore, the acceptable fixatives for Prussian Blue staining are alcohol or 10% neutral buffered formalin.