pathology Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...

, the Grocott-Gomori's (or Gömöri) methenamine silver stain, abbreviated GMS, is a popular

staining Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the ...

method in

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

. The stain was originally named after

György Gömöri György Gömöri (also George Gömöri or George Gomori; 1904–1957) was a Hungarian-American physician who became famous as a histochemist. Gömöri was born in Budapest on 16 July 1904. He received a degree from the medical faculty of the Pá ...

, the Hungarian physician who developed the stain. It is used widely as a screen for

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

s. It is particularly useful in staining carbohydrates. It can be used to identify the yeast-like fungus ''

Pneumocystis jiroveci ''Pneumocystis jirovecii'' (previously ''P. carinii'') is a yeast-like fungus of the genus ''Pneumocystis''. The causative organism of ''Pneumocystis'' pneumonia, it is an important human pathogen, particularly among immunocompromised hosts. Pr ...

'', which causes a form of

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity ...

called ''Pneumocystis'' pneumonia (PCP) or

pneumocystosis Pneumocystosis is a fungal infection that most often presents as Pneumocystis pneumonia in people with HIV/AIDS or poor immunity. It usually causes cough, difficulty breathing and fever, and can lead to respiratory failure. Involvement outside t ...

. The cell walls of these organisms are outlined by the brown to black stain. The principle of GMS is the reduction of

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

ions, which renders the fungal cell wall black. The fungal cell wall commonly contains

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with w ...

. In a GMS procedure,

chromic acid The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixt ...

is first used to oxidize polysaccharides, generating

aldehydes In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

. Then Grocott's alkaline hexamine-silver solution is applied, where the silver ions are reduced to black amorphous silver. The reduction reaction by the fungal cell wall is often known as argentaffin reaction.

References

{{DEFAULTSORT:grocott's Methenamine Silver Stain Staining

See also

References