Marilynn,
You do not detail you fixation/processing protocol, so I have to make the
assumption that you are processing your biopsies the same day you recieve
them.
In my experience, nuclear bubbling or foaming, is a result of processing
the biopsy specimens befor they are adequately fixed in 10% formalin.
Tissues to be fixed in 10% formalin, regardless of size, require  a minimum
24 hours to fix, before they can be processed without causing formalin
fixation artifact (foaming or bubbling of the nuclie).  One way to check to
see if this is the problem, is to examine a few biopsies that fixed in 10%
formalin over a weekend, before they were processed.  These should not show
this artifact. If they do, then you should look at the formalin you are
using or the collection method.  We use recycled xylene with no problems
what so ever, so it should not be part of the problem.
In my lab, where turn around time is also important, and same day
processing is the norm,  we switched to a modified formol acetic acid
alcohol fixative, years ago, for all our biopsies, to avoid this problem.
This fixative gives beautiful nuclear and cytoplasmic details, fixes the
specimen in only a couple of hours, and significantly enhances most
immunohistochemical stains, in particular the so called Keratin 903 stain
that we do on the prostate biopsies. (L26 and S100 are about the only two
antigens not well preseved).  The formula that we use is as follows, 100%
ethyl alcohol -210ml. Con Acetic Acid -15ml. 40% formaldehyde-30ml.
Distilled water -45ml. We suply this fixative to the biopsy O.R.s  so that
the tissues are placed into it as soon as they are taken.  Hope this is of
some help.
Kerry Beebe
Kelowna Gen Hospital
Kelowna B.C. Canada
bbracing@silk.net