How many changes of xylene are recommended to remove alcohol?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

Clearing follows dehydration to replace remaining alcohol with a medium that will mix with paraffin. Xylene serves this role because it dissolves residual alcohol and is miscible with paraffin. A first xylene change removes most of the remaining ethanol, and a second change completes the exchange so the tissue is fully cleared and ready for paraffin infiltration. Using only one change risks leaving some alcohol behind, which can impede paraffin penetration and lead to poorer embedding. More than two changes are not typically needed for standard specimens and would just add time without added benefit. Two changes provide effective clearing with efficient turnaround.