Dear Tim,
We saw something like this on sections that were automatically coverslipped 
on a machine using tape. There was insufficient xylene being droppedonto the 
section to effect proper wetting and adheranceof the tape, leaving the 
section dry and opaque when viewed under the microscope. Try mounting by 
hand with a glass coverslip

Louise Renton
Bone Research Unit
MRC
Johannesburg
South Africa
Tel & fax +27 11 717 2298
"Time flies like an arrow, fruit flies like a banana"





>From: "Coskran, Timothy M" 
>To: "'Histonet@pathology.swmed.edu'" 
>Subject: IHC
>Date: Thu, 12 Dec 2002 14:29:24 -0500
>
>Hello,
>
>Has anyone ever encountered the following type of IHC background problem:
>With two separate antibodies, one a cytoplasmic marker and the other a
>membrane marker, every single nucleus in the section turns brown.  The 
>stain
>itself works, as most of the time you can read through the background, but
>all test slides and negative controls (omission of primary) are affected.
>
>Both antibodies are rabbit polyclonals, both are steam retrieved one with
>citrate pH 6 the other with EDTA.  Both are detected using a whole IgG
>biotinylated goat anti rabbit secondary followed by Elite ABC and Dako
>Liquid DAB+.  Blocks included 3.0% hydrogen peroxide (aq), Dako Biotin
>Blocking system and Dako Protein block.  All were stained on an IHC 
>stainer.
>
>In addition, both of theses antibodies have been reliable for months (using
>the above protocol steps), until now......
>
>Thanks,
>Tim Coskran
>Pfizer
>
>
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