Dear Trisha,

There is a possibility the tissue was not completely dehydrated and/or
infiltrated properly with the MMA.  I am not sure why the student chose to
embed the soft tissue in MMA.  With the paraffins available now, very thin
sections can be achieved and all staining capabilities are accomplished as
well.  

If this precipitate appears to pose a real problem the block can be saved
by cutting away the MMA as close to the block as possible.  Suspend the
remaining portion in pure MMA to dissolve the polymerized portion away
until all the tissue is exposed.  Then reinfiltrate with you protocol and
embed.

Hope this helps.
Regards,
Cathy




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GLP Compliant Laboratory

Cathy A. Mayton
Project Director
Wasatch Histo Consultants, Inc.
www.wasatchhisto.com