Which fixative contains acetic acid and is suitable for preserving tissue morphology?

• A. Zenker
• B. Bouin
• C. Carnoy
• D. Helly

Answer: (A)

Acetic acid in fixatives helps preserve cellular detail and nuclear morphology by promoting rapid fixation and good penetration, although it can cause some tissue swelling. Zenker’s fixative contains acetic acid along with mercuric chloride and potassium dichromate, so it rapidly fixes tissues and preserves overall tissue architecture very well. This makes it a reliable choice when the goal is clear morphology, especially for muscle and connective tissues, where crisp cellular outlines are important. Other acetic-acid-containing options exist, but they have trade-offs: one is very dehydrating and tends to shrink and harden tissue, while another uses hazardous components that can complicate processing and color preservation. So, Zenker’s combination is particularly effective for maintaining morphology while leveraging the acetic acid component.