Which stain is used to demonstrate both sulfated mucopolysaccharides and sulfated sialomucins?

• A. Alcian Blue pH 1.0 and 2.5
• B. PAS
• C. Congo Red
• D. Thioflavin T

Answer: (A)

Alcian Blue is used to visualize acidic mucosubstances because it binds to negatively charged groups on mucins. The binding depends on pH. At pH 1.0, only sulfate groups stay ionized, so sulfated mucopolysaccharides are stained. At pH 2.5, both sulfate and carboxylate groups are ionized, so you stain acidic mucins that are sulfated as well as sialomucins with carboxyl groups. Using Alcian Blue at both pH values lets you demonstrate both sulfated mucopolysaccharides and sulfated sialomucins. The other stains don’t target these mucin types specifically: PAS highlights neutral mucins and glycogen, while Congo Red and Thioflavin T are used for amyloid detection.