Distinctive, rapid, and easy labeling of diffuse plaques in the Alzheimer brains by a new methenamine silver stain.

We have developed a new methenamine silver (MS) stain for detecting diffuse plaques distinctively on paraffin-embedded tissue sections of Alzheimer-type dementia, Down's syndrome, and mentally normal aged brains. This rapid and easy method selectively labels amyloid-related component of senile plaques, but not of kuru plaques found in Gerstmann-Sträussler syndrome. Our MS stain shows almost the same staining pattern as that of the beta protein immunostaining with formic acid pretreatment. Therefore, new MS stain is appropriate to routine or screening studies for senile plaques including diffuse plaques.