Which category of fixatives is associated with forming a sponge-like network in tissue?

• A. Coagulant fixatives
• B. Additive fixatives
• C. Non-coagulant fixatives
• D. Non-additive fixatives

Answer: (A)

Proteins in the tissue are precipitated and denatured by coagulant fixatives, causing them to clump together into a coagulum. This forms a loose, porous, sponge-like mesh that traps water and other components, giving the fixed tissue a spongey appearance under the microscope. This gel-like network is a hallmark of coagulation, which is why coagulant fixatives are the correct category. Non-coagulant fixatives fix tissue by methods like cross-linking or solvent action without creating that precipitated, porous network, so they don’t produce the same sponge-like structure.