Neuritic plaques (also known as senile plaques) are pathological extracellular aggregates formed around a core of amyloid β peptide and are a hallmark of Alzheimer's disease.
They should not be confused with neurofibrillary tangles which are intracytoplasmic.
Neuritic plaques are extracellular and are composed of two components, a central core surrounded by a corona 1,2.
The central core is composed of an aggregate of extracellular beta-pleated amyloid, composed of amyloid β Peptide. It demonstrates apple-green birefringence after Congo red stain and fluoresces after thioflavin S staining 2.
The corona, which surrounds the central core, is composed of degenerating neurons (primarily axons) containing tau protein and ubiquitin.