Fixatives play a vital role in maintaining tissue viability. Commonly used fixatives include: - Formalin: A widely used fixative that preserves tissue by cross-linking proteins. - Glutaraldehyde: Often used for electron microscopy due to its ability to preserve fine cellular structures. - Bouin's Solution: Useful for preserving soft and delicate tissues. Each fixative has its own advantages and is chosen based on the type of tissue and the downstream analysis required.