4% Buffered Glutaraldehyde
25% purified glutaraldehyde 1 part
Phosphate buffer, pH 7.4 5 parts

The solution should be made fresh and used within a few hours. Discard after 8 hours. It was originally recommended for light microscopy because of its effectiveness as a fixative for electron microscopy.

The formula above makes 4% glutaraldehyde at pH 7.4, analogous to 10% NBF (4% neutral buffered formaldehyde) for light microscopy. Kiernan notes that adding 10 mL of 25% glutaraldehyde to 90 mL 10% NBF gives a solution very similar to Karnovsky's fixative used for electron microscopy.

Tissue fixed in this solution has the drawback that free aldehyde groups remain in the tissue following fixation, and any staining method that depends on producing and then demonstrating aldehydes will have positive background staining. Sections must be treated with an aldehyde block to inhibit this staining before producing the aldehyde in such procedures. Analine-acetic is recommended.

Fixation is faster than with formalin, and several hours is sufficient.

There is no special aftertreatment


Culling, C.F.A.,
Handbook of Histopathological and Histochemical Techniques, Ed. 3,
Butterworths, London,, UK.

Kiernan, J. A.,
Histological & Histochemical Methods, Ed. 3,
Butterworth, Heinemann, Oxford.



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