LR White is useful for light microscopic immunolabeling, and
very easy to work with.  We have found that gold labeling with
silver enhancement gives a very pleasing high-resolution result
at the light microscopic level.  Embedding only requires
dehydration through alcohols and heating overnight in an oven
at 55 or 60 degrees C.  It is necessary to exclude oxygen,
however, so completely filled gelatin capsules are usually
used.  Polyethylene embedding molds don't work because they
allow oxygen to penetrate.  Sections can be cut with a glass
knife.  Probably small blocks could be cut on a histologic
microtome.  We got some Unicryl, but we didn't do a careful
comparison.

Incidentally, a good solution to the problem of tissue loss
from frozen sections is the Cryostat Frozen Sectioning Aid
from Instrumedics, which glues the section tightly to the slide.
We use one for frozens of skin of burn patients, and love it.

Hal Hawkins
UTMB Galveston



 ----------
From:  Tora Bardal
Sent:  Tuesday, May 18, 1999 6:25 AM
To:  histonet
Subject:  LR White?

Does anyone out there have any experience with different embedding media
for immunohistochemistry at the LM and TEM level?

At present I use EPON for TEM and LM (sometimes Historesin for LM) and
frozen sections for enzyme- and immunohistochemistry. One problem that
arises with the latter technique is that material in the lumen of gut
sections is washed away during the labelling procedure. I therefore want   
to
try an alternative embedding medium, that infiltrates the tissue and   
keeps
everything in place, and is suitable for immunohistochemistry AND
examinations at the TEM level. I have heard that LR White is an
alternative, but I do not have any experience with it. What are the
advantages (or disadvantages) of this medium compared to others, such as
Unicryl? I need information about polymerisation temperature, special
equipment needed, special procedures before labelling, etc.

Thank you in advance for your help!




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Tora Bardal     tlf: + (47)73 59 09 38
Department of Zoology,    fax: + (47)73 59 63 11
Norwegian University of Science and Technology (NTNU)
Brattoera Research Center
N-7491 Trondheim
Norway