[Histonet] Molds for PMMA Re: Embedding mouse tibia + posterior 1/2 femur

Gayle Callis gcallis <@t> montana.edu
Fri Jul 29 17:22:06 CDT 2005


To avoid breaking glass and having glass shards around, use a polypropylene 
container with screw on lid to avoid any evaporation of the monomer.  If 
evaporation occurs, it changes the consistency of the plastic mixture and 
it ends up funky, rubbery, and hard to cut, Peel a way molds became a no 
no.   Been there, done that - not good!

Polypropylene scintillation (sp?) vials will work, although you can't see 
into them - but cheap.   After polymerization and curing, simply cut off 
the end, or grind it away, and push the block out so it can be shaped to 
fit in block clamp for microtoming or thin 100 um slabs for thick 
sections.  A prepolymerized layer helps as it raises the bone above an 
uneven flat bottom, and the layer does not interfer with polymerization in 
fact it interfaces perfectly with embedding mixture, creates a very clear 
block.  These vials have a lip on them so you have to push away from the 
lip or cut it off too.  A mini hobby band saw works well for this purpose.

We used small plastic, almost clear specimen containers that have wonderful 
flat bottoms - always a plus when working with PMMA.  Erie Scientific under 
the SAMCO Scientific Corp, 800-522-3359, name has O ring lids platic lids 
with these non sterile containers. They are available in 40 ml/48 mm 
diameter, 20 ml/35 mm diameter, along with larger containers.  Contact Erie 
for samples and info.  Other companies have these things, including 
Evergreen Scientific - remember M and M  candies in the specimen container 
samples at NSH conventions - those are the little containers I am referring 
to, and there are some even smaller than the diameters given.

If the bone was small enough - we made  prepolymerized layers in the bottom 
of a 15 ml or 50 ml conical centrifuge tube, embedded on top of the layer, 
then polyermized with the cap on in a 37C waterbath, incubators are shunned 
do to uneven heating.  Or let them polymerize at RT inside a hood, tightly 
capped. After block is cured, cut off conical end, shove block out, shape 
and microtome. Tubes must held down with a weight to prevent floating but 
perfect blocks resulted.

At 03:35 PM 7/29/2005, you wrote:
>Has anybody done PMMA embedding/sectioning of mouse tibia and 
>posterior/distal 1/2 of femur?  If so, what mold/vessel did you use for 
>embedment?  Must one use glass for PMMA or are there other suitable molds 
>out there that will work?

Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

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