Which solvent is universal for dehydration and clearing?

• A. tetrahydrofuran
• B. chloroform
• C. ethyl alcohol
• D. isopropanol

Answer: (A)

The idea being tested is using a solvent that can bridge dehydration and clearing by working with both water and the embedding medium. Tetrahydrofuran fits this role because it is completely miscible with water, so it can take the water out during dehydration. It is also miscible with paraffin, the embedding medium, which means it can transition tissue into the wax without needing a separate clearing agent. This dual compatibility lets THF act as a transitional solvent that handles both steps—dehydration and clearing/infiltration—within one system, which is why it’s described as universal for dehydration and clearing.

Ethyl alcohol and isopropanol are great dehydrating agents but don’t effectively clear and infiltrate with paraffin. Chloroform can clear but isn’t used for dehydration in routine processing. So, THF’s ability to mix with both water and paraffin makes it the best choice for serving as a universal solvent in this context.