Which carbohydrates listed do not require fixation?

• A. Chitin, starch, cellulose
• B. Glycogen
• C. Glucose
• D. Mannose

Answer: (A)

In histology, how a carbohydrate is preserved depends on its solubility and size. Large, insoluble carbohydrate polymers stay in place during routine fixation and processing because they aren’t dissolved or leached out by the fixatives or embedding solvents. Chitin, starch, and cellulose fit this description—they’re sturdy, crystalline polymers that remain in tissues without needing special steps to fix them.

Glycogen, by contrast, is highly water-soluble and is readily lost during standard fixation and processing unless special precautions are taken (like rapid processing or using alcohol-based fixatives to better preserve it). Monosaccharides such as glucose and mannose are small and very soluble, so they are typically washed away during processing and are not reliably retained without specialized methods.

So, the carbohydrates that do not require fixation to stay in tissue during routine processing are the insoluble polymers: chitin, starch, and cellulose.