Which staining technique is useful for highlighting mycotic organisms in tissues?

Grocott's methenamine silver (GMS) stain is specifically designed to highlight mycotic organisms, such as fungi, in tissue sections. This technique uses a silver-based staining method that binds to the polysaccharide components of fungal cell walls, such as chitin and glucan. When applied, this stain not only emphasizes the presence of fungi but also provides a contrasting background, making it easier to visualize the mycotic organisms within the tissue.

GMS is particularly effective in identifying opportunistic pathogens and can aid in diagnosing various fungal infections. The staining mechanism involves reducing silver nitrate, which binds to the fungal structures and then can be visualized under a microscope. This characteristic makes GMS the preferred choice for pathologists when assessing fungal infections in histological samples.

Other staining techniques serve different purposes. Hematoxylin and eosin (H&E) is a general stain commonly used to provide an overview of tissue morphology and structure, but it does not specifically target fungi. Masson's trichrome stain is used primarily to highlight connective tissue and muscle fibers, rather than fungi. Periodic acid-Schiff (PAS) stain can detect polysaccharides in tissues and can stain some fungi, but it is not as specific or sensitive