This not only applies to Histogel but also to support media such as OCT.
Sometimes these may contain salts which can interfere with either IHC or
lectin binding reactions. It is imperative therefore that, if possible,  these
materials be removed prior to the reactions.
At one time OCT contained calcium salts which were actually an advantage in
binding of certain lectins but interfered with the specificity of others.
Barry

amos brooks wrote:

> Ditto,
>     I was the one who asked and I didn't see any either. {:-) You didn't
> miss much Lynn.
>     For those interested The question was in response to someone having
> mentioned that they had seen some light background staining surrounding
> histogel tissue on h(a)ematoxylin and eosin stains. This led me to ask if
> anyone had tried immunohistochemistries on tissue treated this way as the
> background might be intensified by the procedures involved. Special stains
> might intensify this background too, especially silver stains.
> equally befuddled,
> Amos Brooks
>
> Lynn Gardner wrote:
>
> > Dear all,
> >
> > The other day I saw that someone asked if tissue that was in histogel,
> > fixed and processed could be stained for immunohistochemistry. I did not
> > see the answers could someone let me know if this is a possibility?
> >
> > Thanks all!
> > Lynn Gardner