recovery of polymerized mass

From:Cathy Mayton

I am not familiar with the Leica embedding medium but if I remember 
correctly the medium is GMA.  The first thing to do whether it is GMA or 
MMA is to remove the mass from the container, then trim as much of the mass 
away using a band saw.  More than likely the cassettes are at the bottom 
of  the mass.  When you trim be very careful not to cut into the tissue 
specimens.  It will take quite awhile depending on the size of the mass to 
recover the specimens but it can be done.

GMA RECOVERY, place the mass in a gauze bag and suspend the trimmed mass in 
95% ethanol and stir on a magnetic stirrer.  The GMA will soften and can be 
peeled away (it will be gooey).  Keep checking the mass every couple of 
days and change the alcohol as well.

MMA RECOVERY, place the mass in a gauze bag and suspend the trimmed mass in 
stock MMA and stir on a magnetic stirrer.  The MMA will dissolve the mass 
over time.  Again check the mass and periodically change the MMA stock 

Eventually you will get down to the specimens.  Once the specimens are 
recovered you can complete the processing schedule.  Be patient.  It will 
take time but your specimens can be recovered.

Back in the 80's I was infiltrating tissues and had a container with 
cassettes in it that had 1000 ml of GMA.  When I checked on my specimens 
Monday morning I discovered to my horror that the infiltrating medium had 
polymerized.  I did not panic however, because I had experienced the 
problem previously with MMA.  Although it took awhile I was able to 
completely recover the specimens, complete the process and section the 
blocks (even wrote a paper on it).

Anyway, good luck.  Hopefully the investigator will understand that it is 
recoverable but will take time and patience.


GLP Compliant Laboratory

Cathy A. Mayton
Project Director
Wasatch Histo Consultants, Inc.

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