Microglia are a type of non-neuronal cells found within the central nervous system (CNS) of vertebrates, including humans. As the resident immune cells of the CNS, microglia play a vital role in maintaining brain health and functioning. They are a part of the larger group of cells known as glial cells, which provide support, protection, and insulation to neurons.
Microglia are particularly well-known for their immune surveillance and response capabilities within the brain. They act as the first line of defense against pathogens, foreign substances, and brain injuries. When the brain detects an infection, inflammation, or injury, microglia become activated and undergo morphological changes. They transform from a resting state with small round bodies into an ameboid shape, allowing them to migrate to the affected site.
Once activated, microglia release various signaling molecules, such as cytokines and chemokines, which attract other immune cells to the site of injury or infection. They also engage in phagocytosis, a process by which they engulf and digest unwanted cellular debris, dead cells, and pathogens. By clearing away the debris and releasing immune-modulatory molecules, microglia help to restore a healthy environment within the brain.
In addition to their immune functions, microglia also contribute to synaptic remodeling, plasticity, and the maintenance of the neuronal network. They interact with neurons, monitoring their activity and facilitating the formation and elimination of synapses, which are crucial for proper brain development, learning, and memory.
Overall, microglia are important guardians of the brain, serving not only as immune responders but also as critical modulators of neuronal activity and brain plasticity.
