Formal Ammonium Bromide

Formal ammonium bromide
Strong formalin 150 mL
Tap water 850 mL
Ammonium bromide 20 g

Make fresh

Usually referred to as F.A.B., this fixative is often recommended for central nervous tissue, i.e. brain and spinal cord. According to Kiernan, the pH is about 1.5 and it is probably that factor which makes it an effective fixative for tissues on which silver and gold impregnations are to be done to demonstrate the cells and processes of the CNS. It also permits the usual staining methods (H&E etc.).

This fixative should be applied overnight as a minimum, but fixation is not complete until applied for a few days.

There is no special aftertreatment required.


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




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