Which staining technique demonstrates both carboxylated and sulfated mucosubstances?

• A. Schmorl technique for reducing substances
• B. PAS
• C. Alcian blue pH 2.5
• D. Crystal violet

Answer: (C)

Alcian blue at pH 2.5 targets acidic mucosubstances because it binds to negatively charged groups present on these molecules. Mucosubstances with carboxyl groups (carboxylated) and those with sulfate groups (sulfated) both carry negative charges when the environment keeps these groups deprotonated. At pH 2.5, both types are ionized, so the dye adheres to both, letting you visualize a broad range of acidic mucosubstances in the tissue. This contrasts with other stains: PAS highlights neutral mucosubstances, while the Schmorl method detects reducing substances, and crystal violet is not used for mucosubstance differentiation. Therefore, the technique that demonstrates both carboxylated and sulfated mucosubstances is Alcian blue at pH 2.5.