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Table 1 Terminology for main tau assemblies and definition criteria

From: What is the evidence that tau pathology spreads through prion-like propagation?

Name

Definition

Structural criteria

Molecular criteria

Tau pathology

Broad term designing abnormal molecular changes of normal tau as well as morphological changes.

Mislocalization of tau and/or pathological tau assembly in inclusion or aggregate.

Post-translational modifications of tau. Tau insolubility.

Tau inclusion

Morphologically distinct subcellular structure inside a cell.

Microscopically visible structure. Made of tau aggregates.

Properties of tau aggregates.

Tau aggregate

Assembly of tau into oligomers, fibrils, filaments, and NFT

Molecular tau assembly based on highly ordered ß-sheet structure.

Positive with ß-sheet (amyloid) sensitive dyes (Thioflavine T, Congo Red, LCOs). Tau hyperphosphorylation

Tau seed

A tau species inducing aggregation of tau

Molecular tau assemblies of various size providing a template

Positive with ß-sheet sensitive dyes

Liquid coacervates of tau

Membraneless organelles in a state of Liquid-liquid phase separation

Coacervation of tau into liquid droplets

Can acquire ß-sheet structure.

Tangles

Neuronal tau inclusions in somata

Composed of bundles of PHFs and SFs. Gallyas and Campbell-Switzer positive.

3R and 4R tau positive in AD

Neuropil threads

Tau inclusions in nerve cell dendrites

Composed of bundles of PHFs and SFs. Gallyas and Campbell-Switzer positive.

3R and 4R tau positive in AD

Dystrophic neurites

Axons forming the neuritic corona of plaques

Nerve cell processes in contact with Aß deposits. Some of them contain PHFs and SFs and are Gallyas and Campbell-Switzer positive.

3R and 4R tau positive in AD

Argyrophilic grains

Neuronal granular tau inclusions in dendrites

Tau filaments. Gallyas positive. Campbell-Switzer negative.

4R tau positive in AGD

Pick bodies

Spherical tau inclusions in nerve cell somata

Filamentous and vesicular material. Gallyas-negative. Campbell-Switzer positive.

3R tau positive in Pick disease.

Oligodendroglial coiled bodies

Tau inclusions in cell bodies of oligodendrocytes

PHF/SF like filaments. Gallyas positive. Campbell-Switzer negative.

4R tau positive in PSP and CBD

Globular oligodendroglial inclusions

Globular oligodendroglial tau inclusion

Gallyas positive.

Mainly 4R tau positive in GGTs

Tufted astrocytes

Astrocytes with thin and long radial processes containing tau inclusions

Tau filaments in cytoplasm and proximal portions of astrocytic processes. Gallyas positive. Campbell-Switzer negative.

4R tau positive in PSP

Astrocytic plaques

Astrocytes containing tau inclusions in a corona-like arrangment

Tau filaments in distal portions of astrocytic processes. Gallyas positive. Campbell-Switzer negative.

4R tau positive in CBD

Thorn-shaped astrocytes

Astrocytes with thorn-shaped processes containing tau inclusions

Spine-like perinuclear tau filaments. Gallyas positive.

4R tau positive in ARTAG

  1. AD Alzheimer’s disease, AGD Argyrophilic grain disease, ARTAG, Ageing-related tau astrogliopathy, CBD Corticobasal degeneration, GGTs Globular glial tauopathies, PSP Progressive supranuclear palsy, LCOs Luminescent conjugated oligothiophenes
  2. Each of the various tau inclusions is positive with some LCOs
  3. A common feature of all tau assemblies is their immunoreactivity with tau antibodies, although peculiar tau epitopes can distinguish between them. For more details on specific tau inclusions, tauopathies, and silver staining properties see [9, 54, 86, 131]