Bouin's solution contains which combination of ingredients?

• A. Picric Acid, Formaldehyde, Glacial Acetic Acid
• B. Formaldehyde, Glutaraldehyde, Methanol
• C. Picric Acid, Osmium Tetroxide, Formaldehyde
• D. Formaldehyde, Sodium Chloride, Water

Answer: (A)

Bouin's solution is defined by three components: picric acid, formaldehyde, and glacial (concentrated) acetic acid. Each plays a specific role in preserving tissue for histology. Picric acid begins fixation and helps preserve delicate morphology; formaldehyde cross-links proteins to lock cellular structures in place; acetic acid enhances nuclear detail and softens tissue to improve stain uptake. This combination yields excellent overall preservation, especially of nuclei and delicate tissues, which is why it’s a traditional choice for certain specimens. The other options include fixatives or solvents not part of Bouin’s—osmium tetroxide and glutaraldehyde are used for electron microscopy, methanol is a dehydrating solvent, and plain saline is not a fixative.