Which staining technique is used to visualize glycogen in tissues?

The Periodic acid-Schiff (PAS) staining technique is specifically designed to visualize glycogen as well as other carbohydrates in tissues. This method exploits the presence of aldehyde groups that are generated after tissues are oxidized by periodic acid, allowing the PAS reagent to bind and produce a bright magenta staining effect. This makes it particularly effective in highlighting glycogen deposits in various tissues, such as in liver samples where glycogen stores are abundant.

In contrast, hematoxylin and eosin primarily provide contrast for nucleic acids and proteins but do not specifically target carbohydrates. Masson's trichrome is typically used to distinguish between collagen, muscle, and fibrin and does not specifically highlight glycogen. Sudan black is a stain that targets lipids, thus not pertinent when looking for glycogen. Therefore, the specificity of PAS for carbohydrates, especially glycogen, confirms its role as the appropriate staining technique for this purpose.