Which control slide is used with Grocott's Methenamine Silver staining?

• A. Known Fungi Slide
• B. Kidney
• C. Small Intestine
• D. Cerebellum

Answer: (A)

A positive control containing fungi is used with Grocott's Methenamine Silver staining. This control verifies that the silver impregnation and subsequent development are functioning so fungal cell walls appear black against the pale green background, confirming the stain works as intended. The known fungi slide provides a reliable reference: if it shows the expected black fungal elements, you can trust the procedure for patient tissues. If it doesn’t, it flags issues with reagents, timing, or steps that need correction before interpreting other slides. The other tissues listed aren’t reliable positive controls for this stain, because they don’t demonstrate the stain’s ability to detect fungal elements, though they could serve in other roles (like negative controls) in different contexts.