Which statement best describes mercuric chloride as a fixative?

• A. Penetrates poorly and causes excessive shrinkage.
• B. Penetrates quickly and preserves lipids.
• C. Does not react with tissue.
• D. Never forms pigments.

Answer: (A)

Mercuric chloride fixes by forming mercuric-protein cross-links, but it penetrates tissue slowly, especially in thicker specimens. That slow penetration leads to uneven fixation, and the strong fixative effect pulls water out and causes the tissue to contract, resulting in shrinkage. Because of this combination—poor inward movement and significant contraction—excessive shrinkage is a characteristic issue with mercuric chloride fixatives. It does react with tissue and can form mercuric-containing pigments during processing, so the statement about never forming pigments isn’t accurate. It also does not rapidly penetrate to preserve lipids; lipid preservation is not a noted strength of this fixative.