Lab method
GMS silver stain
Silver stain making fungi and Pneumocystis black
G-M-S
High-yield clue
GMS turning organisms black is the classic tissue clue for fungi and for Pneumocystis jirovecii cysts.
Overview
Grocott-Gomori methenamine silver is a histopathology stain in which silver deposits onto fungal cell walls (and Pneumocystis), rendering them black against a pale green counterstain.
Classification
- Silver impregnation concept
- Tissue/histology stain
- Fungal cell-wall stain
- Light microscopy
Lab & identification clues
- Black organisms on pale green background
- Highlights hyphae, yeast, and cyst walls
- Pneumocystis crushed 'ping-pong ball' cyst vocabulary
- Used on biopsy sections
Associations
- Pneumocystis pneumonia tissue association
- Invasive mold detection vocabulary
- Fungal histopathology recognition
Commonly confused with
- Calcofluor white stain
- Acid-fast stain
Your notes
Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.