Which stain highlights fungal cell wall polysaccharides in tissue sections and is often used with PAS?

Which stain highlights fungal cell wall polysaccharides in tissue sections and is often used with PAS?

• A. Grocott-Gomori methenamine silver (GMS)
• B. Hematoxylin and eosin (H&E)
• C. Periodic acid–Schiff (PAS)
• D. Gram stain

Answer: (C)

Periodic acid–Schiff highlights fungal cell wall polysaccharides in tissue sections because fungal walls are rich in carbohydrate components like chitin and glucans. The stain works by oxidizing the polysaccharides with periodic acid to create aldehyde groups, which then react with Schiff reagent to produce a magenta color. This makes yeasts and molds stand out clearly against the surrounding tissue. In practice, PAS is frequently used in combination with diastase digestion (PAS-D) to remove glycogen and reduce background, and it’s common to pair it with another fungal stain such as Grocott-Gomori methenamine silver for confirmation. Among the options, PAS uniquely targets those polysaccharide-rich fungal components, while the others either stain different tissue elements or rely on different staining mechanisms.

Periodic acid–Schiff highlights fungal cell wall polysaccharides in tissue sections because fungal walls are rich in carbohydrate components like chitin and glucans. The stain works by oxidizing the polysaccharides with periodic acid to create aldehyde groups, which then react with Schiff reagent to produce a magenta color. This makes yeasts and molds stand out clearly against the surrounding tissue. In practice, PAS is frequently used in combination with diastase digestion (PAS-D) to remove glycogen and reduce background, and it’s common to pair it with another fungal stain such as Grocott-Gomori methenamine silver for confirmation. Among the options, PAS uniquely targets those polysaccharide-rich fungal components, while the others either stain different tissue elements or rely on different staining mechanisms.