[Histonet] Flash Freezing Brain

[acjanes <@t> bu.edu]

I have a question about flash freezing rodent brains, as sometimes I 
see little holes destroying my tissue and I cannot determine the cause.

Normally I perfuse mice with 4% para, post fix for 1-4 hours with para 
at room temp then put in 30% sucrose until the brain drops (At 4C). 
After this I make an foil mold which I fill with OCT and put my brain 
inside. I then slowly lower the foil/brain mold into a bath containing 
isopentane and dry ice just until everything freezes. I then store the 
tissue at -20 until ready to cut. Normally this works, but occasionally 
I loose tissue to the holes. I am now going to be starting a project 
using rats and I want to make sure all the tissue stays intact. Does 
anyone have suggestions?

We need the tissue to run ICC for c-fos the brains will be cut at 40 
microns using a cryostat.