Fixative for PPB is

• A. 10% NBF
• B. Bouin's
• C. Alcohol
• D. Formalin

Answer: (A)

Fixation aims to lock cellular structures in place so they survive processing and staining without introducing artifacts. For tissue that will be embedded in paraffin and used for routine histology, a neutral buffered formalin fixative is the best choice because it preserves morphology while maintaining a stable pH around neutral. This stability helps prevent acid-induced artifacts and preserves antigenicity for immunohistochemistry, making downstream processing reliable.

Bouin's solution, while excellent for some delicate tissues and nuclear detail, contains picric acid and creates a strong yellow pigment; it’s hazardous, can interfere with staining and IHC, and isn’t ideal for routine paraffin processing. Alcohol fixes tissue by dehydration and can cause shrinkage and hardening, distorting morphology and compromising some stains and downstream analyses. Unbuffered formalin lacks the pH control of neutral buffered formalin, increasing the risk of fixation artifacts and inconsistent results. So, 10% neutral buffered formalin is the most suitable choice for PPB.