[Histonet] HELP! vertical lines in paraffin

Monfils, Paul PMonfils <@t> Lifespan.org
Tue Jan 31 12:15:17 CST 2006

Dirt in the paraffin reservoir of the embedding unit can cause such
problems, but it would really have to be quite dirty to cause the extent of
problem you describe. Have you tried melting the blocks and re-embedding
them in your own paraffin?  When I first started in histology we didn''t
have the quality of commecial products we have today.  We kept a large flask
and funnel in the oven at all times, with filter paper in the funnel.  Newly
opened paraffin was poured into the funnel and allowed to melt and filter
before use, and it was amazing the amount of solid contaminants the filter
paper would collect.  If we used the paraffin without filtering it, we would
get the same kind of problems you are describing.  Today's commercial
products are pre-filtered and much purer.  But a poorly maintained embedding
unit can intruduce contaminants into the paraffin.

> ----------
> From: 	histonet-bounces <@t> lists.utsouthwestern.edu on behalf of
> dgaupp <@t> tulane.edu
> Sent: 	Tuesday, January 31, 2006 9:33 AM
> To: 	histonet <@t> lists.utsouthwestern.edu
> Subject: 	[Histonet] HELP! vertical lines in paraffin
> Histonetters:
> I am having problems sectioning mouse ovary tumor without vertical lines
> from
> the bottom of the block(paraffin only - no tissue touching the blade)  all
> the
> way to top of block.  I did not process/embed these tissues.  So far I've
> done
> the following:
>        1.  changed blades(went threw about 10 just in a few blocks)
>        2.  cleaned microtome
>        3.  changed angles(6-12 degree & everything in between)
>        4.  sectioned hot, cold, freezing
>        5.  soaked blocks in ice cold water; froze blocks
>        6.  surfaced decal 5 - 40 minute intervals
>        7.  re-embedded
> The paraffin seems to be causing the lines!  I've never experienced
> problems
> like this before.  Usually its the tissue itself that causes a nick in
> blade
> which therefore causing vertical lines to appear when sectiong the tissue.
> Help is needed! What next is recommended?
> Dina Gaupp, BS MT
> Tulane University Medical Center
> Center for Gene Therapy
> Histology Core Facility
> 1430 Tulane Ave
> New Orleans, La 70112
> Lab phone 504.988.1194
> email dgaupp <@t> tulane.edu
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