Neuritic plaques
Neurotic plaques which is also known as senile plaques, are pathological extracellular aggregates, that are formed around a core of amyloid β peptide. This types of neurotic plagues are a hallmark of Alzheimer disease. In Alzheimer disease, the basal ganglia of the central nervous system are affected, which is also the seat foe motivation, hence Alzheimer disease is often termed as paralysis of will. Here it is important to mention that neurotic plagues and neurofibrillary tangles are not the same, the latter is intracytoplasmic. Neurotic plaques are extracellular and they are composed of two components, a central core, which is surrounded by a corona. The central core is made of an aggregate of extracellular beta-pleated amyloid. Which demonstrates an apple-green birefringence after Congo red stain and fluoresces after thioflavin S staining. The corona, surrounds the central core, is made of degenerating neurons (primarily axons) containing tau protein and ubiquitin.