Neutral mucins are found in which tissues?

• A. Basement membrane, thyroid and stomach
• B. Lungs
• C. Brain
• D. Heart

Answer: (A)

Neutral mucins are the mucus components that do not stain with Alcian blue but rather are highlighted by PAS, reflecting their neutral carbohydrate makeup. In tissues that produce a protective, non-acidic mucus, such as the stomach’s surface mucous cells, you’ll encounter neutral mucins as a major component of the secreted mucus. The basement membrane also contains mucin-like glycoproteins that can be neutral in charge, contributing to its gel-like, lubricating properties. In the thyroid, there are mucus-containing secretions associated with the follicular cells that can include neutral mucins as part of the secretory milieu. By contrast, the lungs, brain, and heart do not rely on secretions rich in neutral mucins, so they are not characteristic sites for neutral mucins.