Toluidine blue O staining can be used on frozen sections.

• A. It can be used on frozen sections.
• B. It cannot be used on frozen sections.
• C. It requires formalin fixation first.
• D. It stains only lipids.

Answer: (A)

Toluidine blue O is a quick, basic dye used for frozen-section staining. It is water-soluble and can be applied to unfixed cryostat sections, allowing rapid visualization of nuclei and overall tissue architecture without long fixation steps. This makes it suitable for intraoperative or rapid diagnostic contexts where frozen sections are examined. It does not stain lipids specifically, and fixation with formalin is not required for this rapid cryostat staining.