The brain itself is flexible, and there are ways of fixing it in a specialized fixative. The choice of fixative depends largely on; marker of target and nature of the tissue.

However, it is possible a tissue not fixed in chemical if the intention is to prevent disruption of that target marker and that could be made to undergo frozen-section, esp if advanced staining tech such as immunofluorescence is to be performed.

The brain itself is flexible, and there are ways of fixing it in a specialized fixative. The choice of fixative depends largely on; marker of target and nature of the tissue.

However, it is possible a tissue not fixed in chemical if the intention is to prevent disruption of that target marker and that could be made to undergo frozen-section, esp if advanced staining tech such as immunofluorescence is to be performed.

1. Defrost the hippocampus.

2. Immediately make an incision by the midline in the tissue with a scalpel.

3. Then put the sample in 10% formalin pH 7.2 to fix it for at least 2 hrs.

4. Perform the inclusion in paraffin and continue with the histopathology routine technique ...

Cool your fixative (neutral buffered formalin as previously suggested would be good) to between 2-8oC and submerge the frozen brains in the cooled fixative, return to the fridge and give 24-48 hours fixation. This will allow the brain to fix as it defrosts, maintaining the morphology.

I would also agree with Kamoru that frozen sectioning would be a good choice if you have facilities and want immunostaining.

Based on my experience, store in fixative for 24-48 h, when it is hardened, you can make coronal sections in the brain easily ; mid way between frontal and occipital poles.

Nice ideas, however, I am worried that the brains will not be suitable for staining and you could not get the actual view. This because ice crystals will fragment the tissue. Therefore, you should put this into consideration, otherwise, you may misinterpret the histopathology of this tissue.