Why is mercuric chloride avoided for glycogen staining?

• A. Produces an uneven glycogen staining
• B. Gives excessive background
• C. Destroys glycogen completely
• D. Causes strong background coloration

Answer: (A)

Glycogen staining relies on preserving glycogen in place and allowing uniform access of the staining reagents to the stored carbohydrate across the tissue. Mercuric chloride is a heavy-metal fixative that forms mercuric salts and creates strong cross-links within the tissue. This can hinder consistent diffusion and fixation of glycogen in different regions of the sample, leading to patchy, uneven staining where some areas take up the stain more than others. Because of this tendency to produce nonuniform results, mercuric chloride is avoided for glycogen staining. Other fixatives that preserve tissue structure without causing such uneven access—like formalin or paraformaldehyde—are preferred for consistent glycogen visualization.