What is the fixative commonly used for connective tissue?

• A. Bouin Solution
• B. Formalin
• C. Glutaraldehyde
• D. Zinc chloride

Answer: (A)

Bouin's solution fixes connective tissue well because its components work together to preserve the delicate collagen networks and extracellular matrix that define connective tissue. The mix of picric acid, formaldehyde, and acetic acid rapidly cross-links and swells tissue, with picric acid providing excellent preservation and contrast for connective tissue components. This combination enhances staining with common connective-tissue stains (like trichromes), making collagen fibers and other matrix elements stand out clearly while keeping overall architecture intact. While very effective for connective tissue, be mindful that picric acid gives a yellow color and Bouin's must be thoroughly washed before embedding, and it’s not ideal when antigen preservation is needed for certain immunohistochemical tests.