Alcian blue pH 2.5 is used in the demonstration of sulfated mucopolysaccharides only.

• A. True
• B. False
• C. It demonstrates glycogen
• D. It stains proteins at pH 2.5

Answer: (B)

Alcian blue staining depends on the charge of acidic groups in mucopolysaccharides. At pH 2.5, the dye binds not only to sulfated mucopolysaccharides but also to carboxylated ones, meaning it highlights both types of acidic mucopolysaccharides (acidic mucins). Therefore, the demonstration is not limited to sulfated mucopolysaccharides. Glycogen is demonstrated with PAS, not Alcian blue, and Alcian blue does not stain proteins at this pH. This makes the statement false.