Dehydration step in tissue processing accomplishes what?

• A. Removal of water
• B. Addition of water
• C. Staining
• D. Fixation

Answer: (A)

Removing water from tissue is what dehydration accomplishes. By moving the specimen through a graded alcohol series, water is gradually replaced with alcohol, leaving the tissue effectively anhydrous. This step is essential because paraffin wax—the embedding medium—is hydrophobic and cannot infiltrate tissue that still contains water, so complete dehydration enables proper wax penetration and produces intact, well‑preserved sections. After dehydration, a clearing step with a solvent like xylene typically follows to make the tissue compatible with paraffin for embedding. Staining and mounting occur after sectioning, with deparaffinization and rehydration happening before staining. Fixation is performed earlier to preserve structure before dehydration.