Final answer:
Microglia are CNS-resident immune cells that phagocytize cellular debris and pathogens. In the context of neurodegenerative diseases, microglial activity is beneficial in the early clearance of extracellular α-synuclein but becomes inefficient later in the disease, leading to inflammation and oxidative stress. Microglia also interact with degenerated neurons and may accumulate α-synuclein in oligodendroglial cells.
Step-by-step explanation:
Microglia are a type of glial cell in the central nervous system (CNS) that function as the resident immune cells. They originate from white blood cells called macrophages and are responsible for clearing cellular debris and pathogens through a process called phagocytosis.
In the context of the question, microglia play a role in the clearance of extracellular α-synuclein, a protein associated with neurodegenerative diseases like Parkinson's disease. Early in the disease, microglia efficiently phagocytize α-synuclein, but as the disease progresses, they become inefficient and contribute to inflammation and oxidative stress.
Furthermore, the arrival of microglial cells occurs before neuronal cell loss, and their presence leads to the production of pro-inflammatory cytokines and creates oxidative stress. Microglia also surround degenerated neurons containing α-synuclein-positive Lewy bodies, which are immunoreactive to anti-chromogranin-A (CGA) antibody.
Lastly, the accumulation of α-synuclein may also occur in non-myelinating oligodendroglial cells late in the disease.