In Alcian Blue staining, what are the results for glycogen, neutral mucin, and acid mucin?

• A. Glycogen Negative; Neutral Mucin Negative; Acid Mucin Positive
• B. Glycogen Positive; Neutral Mucin Positive; Acid Mucin Negative
• C. Glycogen Negative; Neutral Mucin Positive; Acid Mucin Negative
• D. Glycogen Positive; Neutral Mucin Negative; Acid Mucin Positive

Answer: (A)

Alcian Blue staining at pH 2.5 detects acidic mucins by binding to their negatively charged carboxyl and sulfate groups, giving a blue color. Glycogen and neutral mucins do not have these acidic sites at this pH, so they do not take up Alcian Blue and appear negative. Acid mucin, containing those acidic groups, stains positive. If you need to visualize neutral mucins, you’d use a different stain like PAS (often in combination with AB for differentiation), and glycogen is detected by PAS but not Alcian Blue (diastase can be used to distinguish glycogen from neutral mucins in such combined stains).