Mercury pigment can be removed by immersion in sodium thiosulfate.

• A. True
• B. False
• C. Both
• D. Neither

Answer: (B)

Mercury pigment comes from tissues fixed with mercuric-containing fixatives and appears as a dark, insoluble residue in sections. Sodium thiosulfate is used to dissolve certain silver compounds and fixatives, but it does not effectively dissolve or remove mercury pigments. Because the pigment is not readily complexed or dissolved by thiosulfate in typical histology practice, immersing tissue in sodium thiosulfate does not reliably remove it. That’s why the statement is false. In practice, methods to address mercury pigment differ and often emphasize avoiding mercury-containing fixatives or using alternative demercuration steps, rather than relying on thiosulfate to remove the pigment.