The volume of the fixative should be equal to the volume of the tissue.

• A. True
• B. False
• C. Both
• D. Neither

Answer: (B)

The key idea is that fixation requires enough fixative to surround and penetrate the entire tissue. Diffusion of fixative into tissue is slow, and the fixative reacts as it penetrates. If the fixative volume is only equal to the tissue volume, the fixative near the surface gets depleted quickly and deeper portions may not fix properly, leading to incomplete or uneven fixation. For routine formalin fixation, a fixed-to-tissue volume ratio of about 10:1 to 20:1 is recommended, ensuring the fixative remains in excess and maintains its concentration as fixation proceeds. This supports complete penetration, prevents autolysis, and yields uniform preservation. Therefore, equal volumes are not sufficient, making the statement false.