Which pair comprises the reagents in the Weil staining solution?

• A. Hematoxylin, ferric ammonium sulfate
• B. Cresyl echt violet, Crystal violet
• C. Phosphotungstic acid-hematoxylin, Gold sublimate
• D. Ammonium ferric sulfate, Borax ferricyanide

Answer: (A)

Weil staining is an iron-hematoxylin technique. The dye component is hematoxylin, while ferric ammonium sulfate acts as the mordant and oxidizing agent that forms the active hematein-iron complex and fixes the stain to tissue. This combination gives the characteristic blue-black staining of nuclei and other basophilic structures. The other reagent pairs are used in different stains or yield different color reactions (for example, Cresyl echt violet or Crystal violet for other purposes, PTAH with gold sublimate for muscle or connective tissue, or ferric ammonium sulfate with borax ferricyanide for Prussian blue-type chemistry).