With Alcian blue and hyaluronidase, which mucin components are digested?

• A. Hyaluronic acid and chondroitin sulfate A or C
• B. Glycoproteins
• C. Sulfated mucosubstances
• D. Keratan sulfate

Answer: (A)

This item tests how Alcian blue staining at pH 2.5 interacts with hyaluronidase digestion to identify which mucin components are affected. Alcian blue binds acidic mucosubstances due to their sulfate and carboxyl groups, giving a blue stain to mucins that contain these glycosaminoglycans. Hyaluronidase specifically digests hyaluronic acid and related glycosaminoglycans, including certain chondroitin sulfates. When tissue is treated with hyaluronidase, the stained components that are hyaluronic acid or chondroitin sulfate A or C are digested and lose their staining. Therefore, the components digested by this combination are hyaluronic acid and chondroitin sulfate A or C. Glycoproteins and other sulfated mucosubstances that aren’t hyaluronidase-sensitive will not be removed, and keratan sulfate is targeted by other enzymes, not hyaluronidase.