Which step is part of the Lactophenol Cotton Blue staining procedure?

• A. Do not heat the slide
• B. Gently heat
• C. Use ultraviolet illumination
• D. Stain with charcoal

Answer: (B)

Gentle heating is part of the Lactophenol Cotton Blue staining because it helps the dye penetrate fungal cell walls and clears the background, giving sharper contrast to visualize hyphae and spores. The stain combines phenol to fix and kill the organism, lactic acid to clear, and cotton blue to stain the chitin in the cell walls. Heating should be mild to promote uptake without distorting structures. The other steps aren’t used in this procedure: avoiding heat reduces penetration, ultraviolet illumination isn’t a staining step (it’s a lighting method for fluorescence), and charcoal isn’t part of the Lactophenol Cotton Blue protocol.