Which statement is true about Tetrahydrofuran in tissue processing?

• A. THF will clear tissue for infiltration.
• B. THF will dehydrate tissue.
• C. THF will stain tissue.
• D. THF is a universal solvent.

Answer: (A)

In tissue processing, a clearing step uses a solvent that can remove the last traces of alcohol and be compatible with paraffin so wax can thoroughly infiltrate the tissue. Tetrahydrofuran serves as this clearing agent because it displaces the alcohol and mixes well with paraffin, enabling efficient infiltration of the tissue with molten paraffin. This is why the true statement is that THF will clear tissue for infiltration. Dehydration is done with graded alcohols, not THF. THF does not stain tissue, and while it is a strong solvent, calling it a universal solvent isn’t accurate.