Testing for shrinkage RE: [Histonet] shrinkage/a howlong is a piece of string type question

[gayle callis]

Have you ever thought of doing a shrinkage test?  Take a tissue specimen,
and xerox or use a flat bed scanner.  Put fixed sample between plastic
sheets, and scan it as unfixed tissue, fixed before processing and then
after processing while in a faced paraffin block. Take all the measurements
and then do the calculations./    We used to xerox large stained bone
sections, a clever way of getting a precise macro-images of a huge specimen
to show gross features of a defect. This did a better job than trying to do
a macro-photo with a camera or through a microscope (the latter doesn't
happen).  

Years ago, when preparing for HTL exam practical, the samples e.g. tissue
sections submitted had to be within a certain size range, and it was duly
noted that after processing, the samples had shrinkage.  This required going
back to fixed tissue and cutting a bigger piece to compensate for the
shrinkage and have a final correct sample/section size to follow the
practical rules.  

As for GMA, there is a special processing schedule given to me that does not
use alcohol dehydration (for lipid staining work).  This protocol uses an
GMA/watergradient since GMA is miscible with water.  I would think there
would be even less shrinkage with a water/GMA gradient and the source of
shrinkage would come from the heat of polymerization and possibly a bit from
kind of fixative used.  The heat can controlled to some degree by doing
polymerization on ice, or in a refrigerator, with the round JB4 metal chucks
to dissipate the heat.   

Once again, I agree with Bryan Hewlett's assessment of shrinkage. 

Gayle Callis
HTL/HT/MT(ASCP)
Bozeman MT  


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Edwards,
Richard E.
Sent: Wednesday, August 25, 2010 7:50 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] shrinkage/a howlong is a piece of string type question 



Many  thanks  to  all who  responded, for  paraffin processed tissues the
figures  suggested for the amount of shrinkage found or expected were :-
"more than 5%":"5-10%":"10%"(twice):"10-15%":"20%":"25%":"30-35%":"30-40%",
one  responder felt it was "noticeable" and another thought it was a  "fairy
tale" concocted by pathologists............unsurprisingly many  responders
thought that  the  degree  of  shrinkage was dependent on the fixative used,
processing schedule and the nature of the tissue itself, e.g. amount of
lipid present. As far  as  shrinkage with GMA processed tissue go, a  single
response of "5%"  was quoted.

                                                       Richard  Edwards

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