1. Definition
1.1. Substances used for the preservation of gross and histological specimens of tissue, or individual cells so as to maintain the normal structure of its constituent elements.
2. Usage
2.1. To preserve the tissue
2.1.1. Substances used for the preservation of gross and histological specimens of tissue, or individual cells so as to maintain the normal structure of its constituent elements.
2.2. To prevent postmortem changes like autolysis and putrefaction.
2.2.1. Autolysis: lysis or dissolution of cells by enzymatic action probably as a result of rupture of lysosomes.
2.2.2. Putrefaction: breakdown of tissue by bacterial action often with formation of gas.
2.3. Preservation of chemical compounds and microanatomic constituents
2.4. Hardening
2.4.1. the hardening effect of fixatives allows easy manipulation of soft tissue like brain, intestines etc.
2.5. Solidification
2.5.1. Converts the normal semifluid consistency of cells (gel) to an irreversible semisolid consistency (solid).
2.6. Optical differentiation
2.6.1. it alters to varying degrees the refractive indices of the various components of cells and tissues so that unstained components are more easily visualized than when unfixed.
2.7. Effects of staining
2.7.1. certain fixatives like formaldehyde intensifies the staining character of tissue especially with haematoxylin.