A fixative is a chemical used to preserve the physical and chemical condition of the cells in a tissue and to prevent biochemical and proteolytic activities inside the cell so that the tissue is preserved as close to its original state as possible. In order to perform the above functions efficiently, a fixative must possess certain properties. 

An ideal fixative is one that possesses these properties: 

• Prevents autolysis and bacterial decomposition of cells or tissues so tissue is as near to the living state as possible
• Maintains the shape, size, and volume of the cell as much as possible
• Maintains proper tissue consistency and prevent hardening of the tissue
• Penetrates the tissue completely and quickly
• Can be used for a variety of tissue including lymphoid, fatty, and neural tissues 
• Is compatible with modern automated tissue processors
• Supports high quality staining with H&E
• Supports long-term tissue storage
• Is stable, non-toxic and nonflammable
• Is cost effective 
• Is easy to dispose of