Which tissue serves as the control slide for Alcian Blue?

• A. Small intestine
• B. Grey matter
• C. Infected tissue
• D. Known amyloid slide

Answer: (A)

Alcian Blue targets acidic mucins and related glycosaminoglycans, turning them blue. A reliable control should show a clear, expected blue staining in tissue known to contain abundant mucins. The small intestine fits this perfectly because its mucosal lining is rich in goblet cells that produce mucins, so Alcian Blue reliably stains these cells blue and confirms the staining procedure worked. The grey matter has little mucin, infected tissue varies and isn’t a standard positive control, and a known amyloid slide is not for Alcian Blue (amyloid is typically demonstrated with Congo red), so it wouldn’t provide the expected blue mucin signal.