Fixatives · Pathology

Which of the following fixatives is considered the 'gold standard' for routine histopathology and long-term storage?

  1. Bouin's picric acid fluid
  2. 10% Neutral Buffered Formalin
  3. Buffered glutaraldehyde fixative
  4. Carnoy's fixative solution
Show answer and explanation

Correct answer: 10% Neutral Buffered Formalin

10% Neutral Buffered Formalin is the routine fixative of choice because it is cheap and stable, preserves morphology well, penetrates tissue reliably, and is compatible with most special stains and with immunohistochemistry. Buffering to near-neutral pH is what prevents acid formaldehyde pigment (formalin pigment) from depositing in blood-rich tissue. Bouin's fluid and Carnoy's are special-purpose fixatives, and buffered glutaraldehyde is reserved for electron microscopy.

Difficulty: Medium Question 2 of 20

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