Did you know . . . that once fully fixed, fixed tissues can be stored for a quite a period of time without actually being kept in formalin?
Being able to store fixed tissue this way, is particularly useful for brains, and especially large brains from older calves and cows.
Receiving brains in containers where 90% of the container is occupied by the brain and 10% by formalin is not what we want! It is therefore useful to fix brains in a container with plenty of formalin at the clinic for a day or so, and once fixed the brain can be transferred to/ placed in a plastic bag without formalin, for sending to the laboratory. This saves sending large amounts of formalin in your parcel.
Ascertaining when brains (and other tissues) are fixed is subjective, but once the tissue has some firmness to it, it can generally be considered fixed.
Note: If you continuously fix brains in the same bucket of formalin in your clinic, the formalin will eventually lose strength and the brains won’t fix. Ensure it is replaced frequently.