[Histonet] Re: Testing for shrinkage

[Bryan Llewellyn]

Taking simple measurements of pieces of tissue and then repeating the 
measurements following fixation, processing and infiltration will certainly 
allow for estimating the degree of macroscopic shrinkage.  Unfortunately, 
this is not the only shrinkage that takes place, as a simple look at the 
finished section with a microscope will show.  Cells separated from other 
cells, fibres split off from other fibres, and the like, are all due to 
microscopic shrinkage and are in addition to the macroscopic shrinkage 
determined by simple measurement of tissue.

I have always presumed that this is why Baker's figures appear to be quite 
high, because he factored in all forms of shrinkage, not just the obvious.

Bryan Llewellyn


----- Original Message ----- 
From: "gayle callis" <gayle.callis <@t> bresnan.net>
To: "'Edwards, Richard E.'" <ree3 <@t> leicester.ac.uk>; 
<histonet <@t> lists.utsouthwestern.edu>
Sent: Wednesday, August 25, 2010 8:59 AM
Subject: Testing for shrinkage RE: [Histonet] shrinkage/a howlong is a piece 
of string type question


> 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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