Fixation aims to prevent bacterial degradation and tissue autolysis, preserve intrinsic cellular components, and coagulate or precipitate intracellular substances, tissue fluid, glycogen and other biomolecules. This keeps the chemical composition of cells and tissues nearly identical to their living state, hardens tissues and facilitates sectioning. Fixatives are mainly categorized into aldehyde fixatives, mercury fixatives, alcohol fixatives, oxidant fixatives, and picrate fixatives. Formalin (an aldehyde) and ethanol (an alcohol) are the most widely used types. 4% Glutaraldehyde Fixative consists primarily of glutaraldehyde and phosphate buffer with a pH range of 7.2–7.4. It delivers excellent fixation of fine structures in cell nuclei and cytoplasm, serving as the standard and most commonly used glutaraldehyde fixative for electron microscopy specimen preparation.
Storage: Store at 2–8°C, Store in the dark. Shelf life: 12 months.
Instructions for Use:
1. Immerse fresh specimens immediately in 4% glutaraldehyde fixative and fix at 4 °C for 1–4 hours. Extend fixation time appropriately for larger tissue samples.
2. Submit for testing or store at 4 °C.
Precautions:
1. Glutaraldehyde fixative is corrosive. Handle carefully in a well-ventilated area and avoid inhalation of vapors.
2. Fixation duration varies with the thickness of tissue biopsies. The optimal thickness for routine biopsy tissues is 2–4 mm, and thickness should not exceed 6 mm. Proper trimming of tissue blocks promotes sufficient penetration of the fixative.
3. Use an adequate volume of fixative; the volume ratio of fixative to tissue block shall be greater than 10:1. Replace the fixative 1 to 3 times during fixation if insufficient volume is supplied.
4. Temperature exerts a prominent impact on fixation efficiency. Elevated temperatures accelerate fixation, yet heating is not recommended for this fixative.
5. Fresh tissues must be fixed promptly after dissection. If immediate fixation is unavailable, preserve tissues in normal saline and deliver for testing without delay.
6. Wear a lab coat and disposable nitrile gloves throughout all operations for personal safety and health protection.
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