Neutral mucins are found in which tissues?

• A. Basement membrane, thyroid and stomach
• B. Lungs, brain and liver
• C. Heart, kidney and spleen
• D. Muscle, bone and cartilage

Answer: (A)

Neutral mucins are neutral glycoproteins that react with PAS, highlighting carbohydrate-rich mucous secretions without the acid groups that Alcian Blue would detect. This pattern appears in tissues where neutral mucous is produced or stored. The stomach contains surface and mucous neck cells that secrete neutral mucins to protect the mucosa. The basement membrane is rich in glycoproteins with carbohydrate components, which also stain PAS-positive, resembling neutral mucins in histochemical tests. The thyroid can contain mucous secretions with neutral glycoproteins as well. In contrast, tissues like lungs (which typically have mucins that include more acidic components in goblet cells), brain, liver, heart, kidney, spleen, and musculoskeletal tissues do not emphasize neutral mucins in the same way. Therefore, the combination of basement membrane, thyroid, and stomach best fits tissues associated with neutral mucins.