re-embedding of MMA blocks
Methlymethacrylate (MMA) is a plastic medium
that can be fickle to work with, but a gem when it comes to "saving" tissues
that did not polymerize correctly. Diane and Gayle both put you on the
right path for salvaging the blocks that bubbled during
Like Gayle, I have done many workshops at NSH on
MMA processing and I believe there is a bit of voo-doo that goes along
with MMA processing and it is important to not make the MMA gods angry at
There are several things that can "upset" the MMA
1) the volume present in the container at the time
of polyermization (I have publications that mention polymerizing in
2) vibration (my husband was expanding on my lab
this Spring and was pounding nails and sawing on the new wall)
several of the containers "took off" and had to be re-embedded
3) temperature can be a critical factor and as
Gayle mentioned do not go over 37 degrees.
Whenever possible, I embed in plastic containers
(don't like breaking the glass).
Diane and Gayle told you what I would
have, and that is saw away as much of the MMA as possible. The specimens
can be suspended (I make gauze bags tied with string) in stock MMA (off the
shelf) to dissolve away the bubbles or if needed all the way down to the
specimen. If you only need to remove some bubbles the block can be placed
right back into new mold with fresh embedding medium. If, I recover the
block down to the specimen I at least go back through the second infiltrating
medium and then re-embed the specimen.
Depending on how badly the blocks have bubbled it
may take some time but the tissues are not lost. There are many
publications published in the Journal of Histotechnology during the mid-80's to
late 90's regarding the processing of MMA. Not to worry, your blocks can
be salvaged. I have worked with MMA since 1983 and I still sometimes
upset the MMA gods.
with a Personal Touch"
Cathy A. Mayton, HT(ASCP)
Winnemucca, NV 89445
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