Hi,
    Could this staining have been just tissue you used? This granular staining
in the cytoplasm is sometimes in negative controls, indicating that the reaction
does not involve the antibody and antigen so it can be dealt with as an
artifact. My guess is biotin if it is in a negative control too. If you didn't
run one you might want to consider it, I've seen a lot of things in these
controls that really justifies their use.
    If it isn't in the negative, there might be some contamination in one or
more of the reagents. Try a new batch of TdT first to see if it is the primary
since that is the most likely place.
good luck,
Amos Brooks

Tom Wells wrote:

> We recently came across a case that stained strongly positive with Dako TTF,
> but, instead of the usual nuclear staining the staining was cytoplasmic and
> granular.  Has anyone else seen this staining pattern?  We have performed
> numerous TTF stains before and since and have not come across this before.
> Thanks. Tom
>
> Tom Wells, BSc, ART
> Supervisor, Immunohistochemistry Laboratory
> Lions Gate Hospital
> North Vancouver, BC
> Canada