What is the Origin of Microglia?

Microglia originate early in embryonic development from primitive myeloid progenitors in the yolk sac, establishing themselves in the CNS before the formation of the blood-brain barrier. Unlike other brain cells, they are not derived from the neural tube, maintaining a unique lineage distinct from neurons and other glial cells. The term itself is derived from the Greek mikros (small) and glia (glue), reflecting their early identification as small, supportive cells.

What is the Mechanism of Microglia?

Microglia operate through a mechanism of morphological and functional plasticity, shifting between a resting, surveillance state and an activated, phagocytic state in response to microenvironmental cues. They actively prune redundant or weak synaptic connections, a process essential for circuit refinement and learning. Furthermore, microglia express receptors for and respond to circulating hormones, such as estradiol, which modulates their inflammatory potential and contributes to sex-dependent differences in brain function and neuroprotection.

Microglia

Meaning

Microglia are the resident macrophage cells of the central nervous system (CNS), functioning as the brain’s primary form of active immune defense and homeostatic maintenance. These highly dynamic glial cells constantly survey the brain microenvironment, acting as crucial sentinels for infection, injury, and cellular debris. Their proper function is increasingly recognized as pivotal for neuronal health, synaptic plasticity, and the neuroendocrine regulation of mood and cognition.