Neurofibrillary tangles
Neurofibrillary tangles are pathological protein aggregates found within neurons in cases of Alzheimer's disease. Tangles are formed by hyperphosphorylation of a microtubule-associated protein known as tau, causing it to aggregate in an insoluble form. The precise mechanism of tangle formation is not completely understood, and it is still controversial whether tangles are a primary causative factor in the disease or play a more peripheral role.