Which statement best describes the color pattern in Alcian blue 2.5 staining for sulfated mucins, background, and nuclei?

• A. Dark blue mucins; pink to red background; blue nuclei
• B. Light blue mucins; blue background; pink nuclei
• C. Dark blue mucins; blue background; pink nuclei
• D. Light pink mucins; pink background; blue nuclei

Answer: (A)

Alcian blue 2.5 specifically binds to acidic mucins, including sulfated mucins, and stains them deep blue. When this stain is used in combination with PAS, the background is colored pink by the PAS reaction, while nuclei are counterstained blue by hematoxylin. So sulfated mucins appear dark blue, the background is pink, and the nuclei are blue. This pattern best matches the described staining outcome.