Which solvent is used as the clearing agent following cedarwood oil in the processing sequence?

• A. Xylene
• B. Ethanol
• C. Water
• D. Isopropanol

Answer: (A)

Clearing agents must render the tissue transparent and be compatible with the embedding medium so infiltration can occur smoothly. When cedarwood oil has been used as the clearing step, the next solvent must effectively remove that oil and prepare tissue for paraffin infiltration. Xylene fits this role well because it dissolves cedarwood oil and is miscible with paraffin, allowing the tissue to be ready for embedding. Ethanol, isopropanol, and water are not suitable as the clearing step after cedarwood oil—they either act as dehydration/dehydrating solvents or reintroduce moisture, preventing proper clearing and paraffin infiltration. Therefore, xylene is the clearing agent used after cedarwood oil.