Chemical etching of LR White sections:
This technique has been used to increase the accessibility of the antigenic
sites, or "antigen retrieve" in the section for immuno electron microscopy.
We would recommend the paper "Antigen Unmasking for Immuno electron
Microscopy: Labeling is Improved by Treating with Sodium Ethoxide or Sodium
Metaperiodate, then Heating on Retrieval Medium", Journal of Histochem. and
Cytochem., 43:115-123 (1995).
Staining the sections:
There have been numerous reports in the published literature describing various staining
techniques of immunolabeled sections. Most of them involve the use of
uranyl acetate as a negative stain.
Embedding of Plant Tissue:
For many workers, there is experienced some difficulty embedding plant
tissue with other embedding resin systems. LR White, with its viscosity
that is like water, can be very easily infiltrated (relatively speaking, of
course) and there has
been quite a bit published on the embedding of plant tissue.
The resin itself comes ready to
use and if intended for use at low temperature, one would need
SPI #02648-AB, accelerator which comes in a convenient dropper bottle.
Available in three grades, hard medium and soft, with hard and medium grades
for most users being much more popular than the "soft".
L R White vs. Araldite® 502 Resin embedding
Some comparisons have been made comparing L R White vs. Araldite embedding. The conclusion
was that despite the less rigorous processing associated with the use of LR White,
neither the appearance or the amount of the extracellular material was affected by
the different embedding protocols. We interpret this to mean that some antigenic
sites are more sensitive to alcohol disruption than others, and in this case, the
sites must have been quite resistant to such disruption. But for other systems,
the opposite is true. The point is, for a new system, it is often times worth
trying several different embedding approaches, in order to determine the one that
is the most optimum for that specific situation.
Polymerization:
All three resin grades can be polymerized either chemically, at low
temperature using UV irradiation at 365 nm, or by elevated temperatures, either by conventional
oven or microwave techniques. Note that this resin system is not compatible with
the use of acetone, since the presence of any ketone will inhibit
polymerization.
Each bottle of resin comes complete with five different monographs to provide assistance
to the user of the resin:
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