Final answer:
A preferred fixative is a substance that preserves biological tissues and stabilizes cell structures in tissue samples for observation under a microscope. Fixation is achieved through heat fixing or chemical treatment. Chemical fixatives denature proteins, stop biochemical reactions, and preserve the integrity of cellular components.
Step-by-step explanation:
A preferred fixative is a substance that preserves biological tissues and stabilizes cell structures in tissue samples for observation under a microscope. Fixation can be achieved through either heat fixing or chemical treatment. Chemical fixatives such as acetic acid, ethanol, methanol, formaldehyde, and glutaraldehyde denature proteins, stop biochemical reactions, and preserve the integrity of cellular components in tissue samples. This method is preferable for tissue specimens as it kills microorganisms in the sample and prevents degradation of the tissues.