Pathologic terms:
Neurofibrillary pathology: Neurofibrillary pathology comprises aberrant, partly insoluble, protease-resistant, hyperphosphorylated tau aggregates; by electron microscopy, some have a paired helical filament appearance inside various cellular compartments or extracellular after death of the parent cell. Neurofibrillary tangles (NFTs) and pretangles: The term NFT describes neurofibrillary pathology found in cell bodies. A pretangle is contains abnormal hyperphosphorylated tau in nonfibrillar (partially soluble) and nonargyrophilic form. Some pretangles are capable of developing into NFTs. Amyloid plaques that contain the Aβ peptide (AβPs): AβPs are extracellular, often roughly spherical structures containing Aβ peptide and other material. AβPs in histological preparations may be detected using Congo red, silver stains, and thioflavin-like molecules. Diffuse AβPs may be visualized using silver stains and anti-Aβ immunostains. Neuritic Aβ plaques (NPs): NPs are AβPs that are invested by swollen, degenerating neurites and glial cell processes. The swollen neurites may contain filamentous tau protein aggregates identical structurally to the inclusions within the NFT. The density of NPs is graded according to the Consortium to Establish A Registry for Alzheimer’s Disease (CERAD) criteria (51). By definition, diffuse plaques lack dystrophic tau-immunoreactive neurites. Braak stages: Braak stages (60) refer to the hypothetically predictable progression of NFT-type pathologic features in the brain during the course of Alzheimer disease (AD). In early stages (I–III), the pathologic finding is mostly isolated to the medial temporal lobe structures; later stages (IV–VI) progressively affect the neocortex.
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