Fig. 5
From: The neuropathological diagnosis of Alzheimer’s disease
Paired Helical Filaments and Straight Filaments. Neurofibrillary tangles are composed of insoluble tau filaments that can be extracted using detergents or acids and visualized using electron microscopy and negative staining such as 2% uranyl acetate here. The paired helical filaments (arrows) and straight filaments (arrowheads) both appear to be composed of pairs of 10 nm filaments that wrap around one another with the PHFs exhibiting wider 10–20 nm modulations in diameter and the SFs narrower 10–15 nm modulations. Length bars are 100 nm