Brain Embedding Medium

Tristan Davies tbd at
Fri Dec 6 15:21:21 EST 1991

In article <16NOV199120460769 at> karuzis at (GLENN HOLM) writes:
-->Anyone out there have suggestions for the ideal embedding medium to surround
-->small, fragile brain specimens prior to cutting on vibratome or freezing
-->microtome?  I guess the goal is to find something of the hardness and con-
-->sistency of perfused (4% paraformaldehyde) brain tissue that can be cast as
-->a block and then sectioned (around 30 microns) to produce easy to handle
-->free floating sections.  Something on the order of liquid brain.

You left out a couple of details:
1.  Is the tissue you're cutting fixed? with what?
2. How thick do you want your sections?
3. Are you only using them for immunocytochemistry?

OK, three details that I can think of.

I don't know of other techniques, but I wouldn't dismiss the ones you've 
already tried yet.  I've had good luck cutting 15-20 um and thicker Vibratome 
sections from brains embedded in  albumin/gelatin.  
I think cryostat sections are the gold standard for immunostaining, and 
you don't have to keep cryostat sections in the freezer after you react and 
coverslip them!
As for frozen sections on a sliding microtome, we simply "embed" the tissue
by surrounding it with water and letting it freeze.  Works fine!
Also, I've done a lot of immunostaining of paraffin sections on slides.  A
little cumbersome havong to handle the slides, but it's easy to keep sections
in serial order, and if the antigen survives, the tissue preservation and 
morphology are immensely superior to cryostat sections.
For other imbedding ideas, you might explore some catalogs, e.g. Ted Pella,
which sells EM supplies and Vibratome accessories, or even Baxter or Fisher,
which supply a lot of hospitals' pathology labs.
Hope this helps!

Tristan Davies

e-mail: tbd at
Department of Neurobiology, Duke University Medical Center

"grblb blabt unt mipt speeb!! oot piffoo blaboo..." -- Opus

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