Urate crystals require fixation with which type of fixative?

• A. An aqueous based fixative such as absolute alcohol
• B. Non-aqueous fixatives only
• C. Acetone or acetone-based fixes
• D. Xylene-based fixes only

Answer: (A)

Urate crystals stay intact when they are in a water-containing environment. Fixation in an aqueous fixative provides the necessary water to keep the crystal lattice stable during processing. When tissues are fixed with dehydrating, non-aqueous fixatives, water is removed and the urate crystals can dissolve or be altered, making them difficult to see under the microscope. Therefore, using an aqueous-based fixative best preserves urate crystals, whereas non-aqueous fixes like acetone, certain alcohols, or xylene tend to dissolve or displace them.