The primary purpose of fixation is to

• A. To stop enzymatic action
• B. To harden tissue for cutting
• C. To remove lipids
• D. To stain tissue

Answer: (A)

Fixation is all about preserving the tissue by stopping the enzymes that would otherwise break it down after removal from the body. By inactivating endogenous enzymes and cross-linking proteins, fixation halts autolysis and stabilizes cellular structures so the tissue keeps its morphology when it’s processed further for embedding, sectioning, and staining. This stabilization is what lets you obtain meaningful, crisp histological sections.

Hardening the tissue for cutting happens as a consequence of the chemical cross-linking, so it’s a helpful side effect but not the primary goal. Removing lipids isn’t the main purpose of fixation—lipid preservation or extraction depends on the specific fixative and processing steps. Staining occurs after fixation, so fixation itself isn’t performing the staining.