Gridley’s Fungus Stain demonstrates fungi in tissue. Which structure is stained deep purple?

• A. Mycelia
• B. Conidia
• C. Background
• D. Nuclei

Answer: (A)

Gridley’s Fungus Stain is designed to highlight fungal elements by staining their cell walls, making those structures stand out against the surrounding tissue. Fungal hyphae form the mycelial network, and their cell walls contain compounds that bind strongly to the stain, producing a deep purple color. This makes the filamentous hyphae easily identifiable in tissue sections. Spores (conidia) may appear as small features, but they are not the primary structures targeted for a deep purple stain in this method. Background tissue and nuclei typically do not take on that intense purple hue, so the deep purple structures you see are the fungal filaments—the mycelia.