Generally an increase in the temperature of the fixative solution will have which effect on fixation?

• A. Will increase the speed of fixation
• B. Will decrease the speed of fixation
• C. No effect
• D. Causes the fixative to evaporate

Answer: (A)

Raising the temperature generally speeds up fixation because both diffusion and the chemical reactions that cross-link tissue proteins occur more rapidly when molecules move faster. Higher temperature increases molecular motion, so fixative molecules penetrate the tissue more quickly and form cross-links faster, shortening the time needed to achieve fixation.

In practice, this means fixation proceeds faster as temperature rises, but there’s a caveat: pushing temperature too high can cause artifacts such as tissue distortion, over-fixation, or drying/evaporation issues, which can compromise results. Other options aren’t as correct because fixation does respond to temperature changes, and evaporation is a potential concern only at extreme conditions, not the primary effect on fixation speed.