Alcian Blue-PAS-Hematoxylin is used to differentiate between which types of mucosubstances?

• A. Acidic and neutral mucosubstances
• B. Nuclei and cytoplasm
• C. Amyloid and collagen
• D. Mucin and protein

Answer: (A)

The test is about differentiating types of mucosubstances in tissue using a combined stain. Alcian Blue at pH around 2.5 binds to acidic mucopolysaccharides and sialomucins, turning them blue. The PAS portion oxidizes sugars to form aldehydes and then reacts with Schiff reagent to color neutral mucosubstances (and glycogen) magenta. Hematoxylin provides a blue counterstain for nuclei and general tissue context, but it does not differentiate mucosubstances itself. When both acidic and neutral mucosubstances are present, you can see a mix of blue and magenta, often resulting in purple areas where they overlap. This method is not intended to distinguish nuclei from cytoplasm (that’s what H&E does), nor is it used to separate amyloid from collagen (specific stains like Congo red or specialized stains are used for that), nor to simply differentiate mucin from protein outside the acidic/neutral mucosubstance context.