The chief objection to the clearing agent xylene for processing tissues is that xylene is:

• A. Likely to harden tissue
• B. Flavorful
• C. Non-toxic
• D. Expensive

Answer: (A)

Clearing agents like xylene must remove alcohol and replace it with a solvent that is compatible with paraffin. Xylene is a very strong, aggressive solvent, and its action on tissue can strip lipids and cause shrinkage. This loss of lipids and the associated dehydration can make the tissue less pliable and more brittle, so sections may end up hard or brittle if exposure is excessive or processing steps aren’t balanced. Among the given options, describing xylene as likely to harden tissue best captures how its solvent power can adversely affect tissue quality. The other choices aren’t fitting: xylene isn’t flavorful, it isn’t non-toxic, and while cost can be a concern, it isn’t the primary drawback in the context of tissue processing artifacts.