In the LCB procedure, what should be done after transferring the sample to the slide?

• A. Apply a few drops of stain
• B. Heat fix the slide
• C. Wash with water and air dry
• D. Invert the slide onto a culture plate

Answer: (A)

In this staining step, the goal is to create contrast so fungal structures can be seen clearly. After placing the sample on the slide, you add a drop of lactophenol cotton blue. This solution acts as both a mounting medium and a stain, coloring the cell walls and making hyphae, spores, and conidia easy to observe under the microscope. Heating the slide is avoided here because it can distort fungal morphology, and washing with water would remove the stain and disrupt visualization. Inverting onto a culture plate isn’t part of preparing the slide for viewing. So the next action is to apply a few drops of stain.