Carnoy's solution should not be used for longer than 4 hours because it causes which tissue changes?

• A. Excessive shrinkage and hardening
• B. Increased swelling
• C. Decolorization
• D. Loss of nuclear detail

Answer: (A)

Exposure time to fixatives directly shapes tissue morphology, and Carnoy's solution is a strong dehydration fixative that acts quickly by removing water and lipids from tissue. If tissue sits in it too long, dehydration becomes excessive, causing the structure to collapse and the surrounding matrix to tighten. The result is pronounced shrinkage and hardening, which distorts architecture and makes sections brittle. That’s why prolonged use beyond about 4 hours leads to those changes. Increased swelling, decolorization, and loss of nuclear detail are not the primary outcomes of extended exposure to this fixative.