Which practice best preserves glycogen when using formaldehyde with alcohol diluent?

• A. Substituting alcohol as the diluent
• B. Increasing fixative concentration
• C. Adding sugar to fixative
• D. Warm fixation

Answer: (A)

Glycogen is highly soluble in water, so it tends to be lost from tissue when a fixative is used in an aqueous environment. Using formaldehyde with an alcohol-based diluent creates a non-aqueous setting in which glycogen is less likely to diffuse out of the cells while the fixative still cross-links proteins. This alcohol diluent preserves the glycogen content better than water-containing diluents, making it the best practice for keeping glycogen intact during fixation. Increasing fixative concentration won’t address the lack of water control, warm fixation can promote diffusion and leaching, and adding sugar to the fixative doesn’t prevent glycogen loss.