Light (LM) and electron (EM) microscope comparisons of the cytochemistry and immunocytochemistry of
neuritic plaques and neurofibrillary tangles, the main histopathological changes in the brains of
Alzheimer's disease sufferers, have been almost impossible because of the disparity between the two technologies. By embedding unosmicated brain tissue in the
acrylic resin LR White, direct comparisons can be made between techniques applied at the LM level with those at the EM level. After partial
dehydration in 70%
ethanol, the tissue is embedded by rapid infiltration and polymerization at 0 degrees C, which has been shown to maximally preserve tissue immunoreactivity. Semithin sections are then receptive to routine LM stains,
silver stains e.g. Gomori's
methenamine silver, and immunocytochemistry with immunoperoxidase or immunocolloidal
gold. Serial thin sections are stable in the EM and can be immunolabelled and directly compared with their LM counterparts. Results from the use of a mouse
monoclonal antibody against
beta-amyloid and a rabbit polyclonal antibody against
ubiquitin are presented.
LR White resin includes no elements other than
carbon,
oxygen and
nitrogen, of which it is composed, so that sections of it are valuable for sensitive X-ray energy dispersive microanalysis.