This sounds like your tissue is not well dehydrated and cleared. When those steps are inadequate, the paraffin cannot impregnate the tissue adequately. The alcohol and xylene then evaporate, leaving the sinkhole in the tissue. 

My 2 cents worth, j:>)
Joyce Weems
Pathology Manager
Saint Joseph's Hospital 
5665 Peachtree Dunwoody Rd NE
Atlanta, GA 30342
404-851-7376 - Phone
404-851-7831 - Fax




-----Original Message-----
From: histonet-bounces@lists.utsouthwestern.edu
[mailto:histonet-bounces@lists.utsouthwestern.edu]On Behalf Of Timo
Väisänen
Sent: Monday, June 05, 2006 9:54 AM
To: histonet@lists.utsouthwestern.edu
Subject: [Histonet] (no subject)


Dear all,

Has anyone encountered the following problem? The surface of newly embedded
paraffin blocks start to become concave only after few days. This is not a
problem with normal tissue specimens but with for example small biopsies the
uneveness creates difficulties. Biopsies on the edge of the block run out if
you try to trim the block enough to get the samples in the middle of the block
to the same section with the other samples. I quess paraffin can contract but I
have always thought that this takes years. Could there be something wrong with
the paraffin? Any suggestions?   
Thank's in advance,

Timo 

Timo Väisänen PhD 
Oulu University Hospital
Department of Pathology
Finland









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