Retention of glycogen during fixation is thought to result from what?

• A. Entrapment by fixed proteins
• B. Adsorption to lipids
• C. Evaporation during processing
• D. Cross-linking to DNA

Answer: (A)

Glycogen retention during fixation is best explained by entrapment within the fixed protein network created by aldehyde fixatives. When tissues are fixed with agents like formaldehyde, proteins form cross-links that create a stable, mesh-like matrix. This matrix can physically trap glycogen molecules, keeping them from diffusing out during subsequent dehydration and processing steps. Since glycogen is water-soluble, without this network it would be lost during processing.

Adsorption to lipids isn’t a mechanism for glycogen, which is not lipid-soluble. Evaporation during processing isn’t the reason glycogen is retained, as fixation and processing rely on chemical interactions, not vapor loss. Cross-linking to DNA isn’t how glycogen is retained either; the retention comes from being held within the protein cross-link network, not from sticking to nucleic acids.