Postembedding staining of brain tissue for ultrastructural visualization of amyloid in Alzheimer's disease.

A postembedding staining method is presented for ultrastructural visualization of amyloid deposits in brain sections from patients with Alzheimer's disease. Methenamine silver stain is applied to thin sections of tissue embedded in the acrylic resin LR Gold. Senile plaques are easily labeled by silver granules and the ultrastructural detail is well preserved. When staining time is prolonged, silver precipitate also is deposited on neuronal paired helical filaments. This method overcomes the drawbacks of previously reported applications of the stain on Vibratome and Epon sections. Thin sections from the same tissue block can be immunostained with antibodies to various plaque components, thus allowing comparative studies at the electron microscope level.