Re: frozen mouse brain

From:"J. A. Kiernan"

Cynthia Favara wrote:
> I am requesting thought on long term storage of mouse brain. My current
> protocol is to take  one half fresh or NBF fixed,  sucrose protected mouse
> brain usually between 10 and 14 days. Surround with OCT freeze over liquid
> nitrogen and store in -80C.

What is meant by "freeze over liquid nitrogen?" For a specimen as
big as a whole brain of a mouse the only acceptable way to get
freezing (essential if you don't want ice crystal holes) is to
immerse in a liquid - isopentane is the easiest one to use - that
has been pre-cooled to liquid N2 temperature. Thin slices can be
frozen on a very cold metal block, but a mouse's brain isn't a
thin slice. With cryoprotection, fixed objects as thick as 1 cm
can be frozen on a cold metal block well enough for most light 
microscopy applications.
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1

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