RE: [Histonet] Large Sections: Prostate

From:Gayle Callis

Dear Shirley et al.

I loved your description of how to work with large tissues!!

Another embedding suggestion:  If you have an oven set at 60C, preheat your 
wooden block (use hard wood and not soft pine) in the 60 C oven..  Then add 
paraffin to your preheated embedding mold, fill with paraffin, add tissue, 
then place a 60C preheated plastic cassette bottom   on top of tissue as a 
spacer, then place the heated wooden block on top of the spacer.  Remove 
this whole combination of things from oven and place on embedding center to 
harden paraffin or on top of a solid block of ice in a cake pan.
We found this to be less messy than mounting a block holder into paraffin 
and very fast when dealing with numerous blocks.  The wooden block will be 
firmly embedded in back of block to keep things very solid during sectioning.

An excellent embedding mold is the L's with metal plate, you can shape the 
L's into block size you need, and embed outside an oven, try EM 
Sciences.  Release of block is instantaneous after paraffin hardens.

I have seen people use the ring style plastic molds in the same way to hold 
the block in a microtome, but the harder back is superior than something 
paraffin filled - more stable.  Thermo Electron i.e. Shandon had an 
article  on how to do this some years ago, you could ask them and look at 
the photos.

There used to be hard rubber blocks and may still be available, check 
Electron Microscopy Sciences on the off chance they have these.  They are 
excellent for large paraffin blocks, harder than soft wood.  If I still had 
mine, I would send off to you - alas - long gone!

We used to do this with large bone slabs (distal ends of sheep tibias) for 
sledge microtome sectioning.

You can buy 2 x 2 slides from Brain Research and coverglasses too. Also 
Arthur Thomas has a huge selection of oversize coverglasses at various 
thicknesses.  Check with Erie Scientific for oversize slides, we used to be 
able to buy large size from Fisher, but Thomas or Brain Research had them 
in catalogs.

Good luck

At 08:19 AM 3/16/2006, you wrote:
>Hi Chris,
>Actually you can do this yourself, I have mounted the prostate gland on a 2
>by 2 slide if not too large.  Make sure the knife clearance is adequate for
>larger blocks on your microtome or it will not work.  You will have to have
>a sliding microtome for the job.  The embedded block can be mounted on a
>block of wood the size of the cassette to fit into your chuck.  The tissue
>is processed pretty much like your regular specimens if cut thin enough.
>The specimen can be wrapped in lens paper used to clean scopes by stapling
>the edges.  After processing, use a slide box to embed in paraffin and cut
>off the excess after solidified.  Mount it on your wooden block by heating
>the back of the paraffin block and submerging into ice water.  The 2 by 2
>slide may be purchased from a photography shop or some slide vendors can
>supply these.  I have adapted one of the 30 slide racks for the 2 X 2
>slides, had the guys in maintenance cut one side down and reassembled it,
>but some vendors also sell that size rack.  If you need more details you may
>contact me.
>Shirley Powell

Gayle Callis HTL, HT, MT(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717

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