Which statement is true about acids used to decalcify specimens?

• A. Formic acid and nitric acid are used to decalcify specimens.
• B. Formic acid is used, but nitric acid is not.
• C. Nitric acid is used, but formic acid is not.
• D. Neither formic nor nitric acid is used.

Answer: (A)

Decalcification with acids is used to remove mineral content from calcified tissues so that thin sections can be cut without distortion. Both formic acid and nitric acid are commonly used for this purpose, though they behave differently. Formic acid is a milder, slower decalcifier that tends to preserve tissue morphology and some antigenicity, making it suitable when downstream staining or immunohistochemistry is planned. Nitric acid is stronger and accelerates decalcification, which is helpful for faster processing but can increase tissue damage and over-decalcification if not carefully timed. Since both acids are actually used in practice, the statement that formic acid and nitric acid are used to decalcify specimens is true.