[Histonet] Attention Daniel Blackburn about plastics embedding

[Gayle Callis]

You wrote: 

 

My lab hopes to get into plastic sectioning.  We need to be able to process
tissue pieces as large and thick as possible, but see that the largest
embedding molds for JB4 are only 13x19mm by 5mm deep.   We have two
questions:  (1) Do any of the available media (plastic or resins) allow one
to embed and section large  pieces (for example eggs with dimensions of 2 cm
or larger)?   (2) Is a special microtome (such as a retracting microtome)
needed?   Our reason for considering plastic is that we must section yolk,
which splits out of standard paraffin during sectioning. Any advice is
appreciated. -- Daniel Blackburn, Trinity College 

 

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Glycol methacrylate is not designed for samples as large at 2 cm.  However,
I have one publication from an old Stain Technology for large
chondro-osseous (sp?) sample.   I also have a protocol from a lady who used
water based processing with GMA since it is water miscible.   This was a
protocol lipids which are removed by organic solvents.   You might be able
to develop a protocol with your 2 cm samples.   Kits are expensive and I
have information on making up GMA in house.   Hope you have a good fume
hood!!  As you can see from another post today, GMA contains sensitizing
chemicals, and a carcinogen.  It will require double gloving with nitrile
gloves, and other personal safety gear.   The fume hood is an absolute must
have. 

 

You will need a powerful microtome, i.e. Leica 2250 or 2265 or equivalent,
with very sharp knives, maybe even tungsten carbide.  We used glass knives
on a JB-4 microtome but I have a colleague who used a 2250 and disposable
microtome blades, but you blocks are pretty large.   You may want to
consider using Peel away molds which come in several sizes.   With your size
sample, infiltration and polymerization will be tricky.  You have to seal
air away from the top of molds in order to get the blocks to polymerize.  I
think people have used plastic wrap over the top of molds to exclude air
although our metal blocks fit in the embedding molds snugly and we did an
old school method to exclude air.  Melted paraffin around outside of molds,
a messy but effective air block.   

 

Please contact me personally and I will send this this information to you.
I think you can do this with a reply to all after reading this message.   

 

Take care

Gayle Callis HTL, HT, MT(ASCP)

GCallis Histology Service LLC

Bozeman MT/USA