The lactophenol cotton blue (LPCB) wet mount preparation is the most widely used method of staining and observing fungi and is simple to prepare. The preparation has three components: phenol, which will kill any live organisms; lactic acid which preserves fungal structures, and cotton blue which stains the chitin in the fungal cell walls.
Procedure for corneal scrape material:
Place a drop of 70% alcohol on a microscope slide.
Immerse the specimen/material in the drop of alcohol.
Add one, or at most two drops of the lactophenol/cotton blue mountant/stain before the alcohol dries out.
Holding the coverslip between forefinger and thumb, touch one edge of the drop of mountant with the coverslip edge, and lower gently, avoiding air bubbles. The preparation is now ready for examination.
Fungal hyphae in corneal tissue stained by lactophenol cotton blue
Photo: Philip Thomas