Screening for neurofibrillary tangles and argyrophilic plaques with Congo Red and polarized light.

The capricious nature of silver impregnation tech- niques renders them unsuitable for bulk staining and screening sections for the presence of argyrophilic (senile) plaques and neurofibrillary tangles. For this purpose, we describe a simple, consistent and highly sensitive bulk staining method. It depends on the congophilia and resultant anomalous colour or polarization (Ladewig, 1945) that characterizes amyloid and other fibrillary protein components of plaques and tangles (Terry and Wisniewski, 1970).