Formalin is a coagulative fixative and is considered an excellent fixative for paraffin embedding.

• A. True
• B. False
• C. Not sure
• D. Not applicable

Answer: (B)

Formalin is a crosslinking fixative, not a coagulative one. It fixes tissues by forming methylene bridges between proteins, which preserves cellular architecture and makes tissues stiff enough for reliable paraffin infiltration and thin sectioning. That crosslinking action is why formalin is widely used and considered excellent for paraffin embedding. The statement is incorrect only in labeling formalin as coagulative; the practical use for paraffin is true, though keep in mind that crosslinking can mask antigens and may require antigen retrieval for certain immunohistochemical stains.