GMS Stain Service: High-Sensitivity Detection of Fungi and Microorganisms

At iHisto, we offer high-precision Grocott’s Methenamine Silver (GMS) staining for clear visualization of fungal organisms, Pneumocystis jirovecii, and select bacteria in tissue sections. This silver-based stain is essential for infectious disease research and clinical diagnostics — especially when routine stains fail to reveal pathogens.

🧪 Overview

The GMS stain is a silver impregnation technique that highlights carbohydrate-rich microbial walls, turning fungal elements black against a light green background. It is highly effective for detecting fungi and Pneumocystis in FFPE tissue sections, especially in:

• Immunocompromised models

• Opportunistic infections

• Preclinical drug studies

iHisto’s optimized protocol ensures excellent contrast and minimal background, supporting accurate diagnosis and infectious burden assessment.

⚙️ How the GMS Stain Works 

GMS staining involves a series of oxidation and silver-reduction steps. Fungal walls and Pneumocystis cysts oxidize to expose aldehyde groups, which bind silver. Silver nitrate is reduced by methenamine into black silver chromate that deposits in microbial structures.

Color outcomes:

• Fungi / Pneumocystis / select bacteria: black

• Background / tissue / cytoplasm: pale green to colorless

• Nuclei (optional): lightly stained depending on counterstain

🧬 Step-by-Step Staining Process

1. Fixation and Sectioning
   FFPE tissue is cut at 4–5 µm and mounted on charged slides.

2. Deparaffinization and Hydration
   Standard xylene and alcohol series into distilled water.

3. Oxidation
   Chromic acid oxidizes fungal walls, enhancing silver binding.

4. Methenamine Silver Treatment
   Heated methenamine silver nitrate solution reduces silver at fungal sites.

5. Toning and Fixation
   Gold chloride enhances contrast; sodium thiosulfate removes unreduced silver.

6. Counterstaining and Coverslipping
   Light green or hematoxylin adds tissue contrast. Slides are then dehydrated, cleared, and coverslipped.

🔬 Applications of GMS Staining 

GMS staining is critical when H&E or PAS fail to reveal fungal structures or microbial burden.

Common applications include:

• Diagnosing fungal infections (Aspergillus, Candida, Histoplasma, Cryptococcus)

• Detecting Pneumocystis jirovecii in lung tissue

• Chronic granulomatous infections

• Fungal burden analysis in drug trials

• Preclinical sepsis or immunosuppression models

✅ Why Choose iHisto’s GMS Staining Services 

• ✅ High-contrast, sensitive detection of fungal pathogens

• ✅ Minimal background with precise silver reaction control

• ✅ Works on human, rodent, and non-human primate tissue

• ✅ Optional whole-slide scanning and cloud delivery

• ✅ Pathologist review available for quantification or interpretation

iHisto supports infectious disease labs, CROs, academic research, and clinical pathology with reliable silver stain results.

❓ FAQs 

• What does the GMS stain detect?
  Fungi, Pneumocystis jirovecii, and certain bacteria via their carbohydrate-rich cell walls.

• Is GMS better than PAS for fungi?
  Yes — it provides higher contrast and greater sensitivity, especially for small fungal elements and Pneumocystis.

• Can GMS stain be used in animal studies?
  Absolutely — it’s validated for use in mouse, rat, NHP, and other preclinical models.

• Do you offer digital delivery of stained slides?
  Yes — slides are available as high-resolution scans via HistoCloud or encrypted offline media.

📩 Request a Quote or Consultation 

Whether you're diagnosing fungal infections, evaluating therapeutic efficacy, or studying infectious disease models, iHisto delivers GMS staining with precision, speed, and expert support.

👉 Request a Quote or email us at info@ihisto.io