Mercuric chloride fixatives should be avoided for glycogen fixation due to?

• A. Produces uneven glycogen staining
• B. Causes excessive shrinkage
• C. Too slow to fix
• D. Expensive

Answer: (A)

Glycogen is water‑soluble, so how a fixative interacts with the tissue determines how well glycogen is preserved through processing. Mercuric chloride fixatives fix tissue by precipitating proteins, but they don’t reliably lock in soluble glycogen. During subsequent dehydration and processing steps, glycogen can be leached out or unevenly retained, producing patchy or inconsistent (uneven) glycogen staining when you stain for glycogen (such as with PAS after diastase treatment). That unreliability is the main reason mercuric chloride fixatives are avoided for glycogen studies.