Excess Bouin should be removed before processing.

• A. True
• B. False
• C. Depends on tissue
• D. Not required

Answer: (A)

Bouin's fixative contains picric acid, which can leave residue that interferes with processing and staining. Removing the excess Bouin before processing leaches out the picric acid and acetic acid, reducing artifacts and safety risks and allowing proper dehydration and paraffin infiltration. Thick yellow coloration and background staining can occur if residual fixative remains, making nuclear details harder to see. Thorough washing with running water (often for several hours to overnight) is the standard step to prepare Bouin-fixed tissue for processing. The exact wash time may vary with tissue size, but the need to remove excess Bouin before processing is consistent.