In biopsy processing, which step lasts 60 minutes?

• A. 80% alcohol.
• B. Absolute alcohol.
• C. Xylene.
• D. Paraffin.

Answer: (B)

The main idea is dehydration timing in biopsy processing, specifically the final dehydration step. In histology, tissue is moved through a series of alcohols to remove water, with the last stage using absolute (100%) alcohol to ensure all water is gone before clearing and embedding. This step is often set for about 60 minutes in many biopsy protocols because thorough dehydration is crucial for proper paraffin infiltration. If water remains, it can interfere with clearing and embedding, leading to poor tissue infiltration and artifacts during sectioning.

The other options don’t fit this timing role: 80% alcohol is an earlier dehydration step and generally used for a shorter duration; xylene is the clearing agent used after dehydration; paraffin is the embedding medium that follows clearing and infiltration, not a dehydration step.