Gliacelle

Gliacelle, or cellule gliali, are non-neuronal cells of the nervous system that provide support and protection for neurons. They outnumber neurons in many brain regions and are essential for the structure and function of neural networks.

In the central nervous system, the main glial cell types are astrocytes, oligodendrocytes and microglia, along with ependymal cells that line the ventricles. In the peripheral nervous system, Schwann cells and satellite glial cells perform related roles. Glial cells originate from the neural tube, with microglia arising from the yolk sac and the others deriving from neural ectodermal lineages.

Key functions of gliacelle include structural support for neurons, regulation of extracellular ion balance and neurotransmitter levels, and provision of metabolic substrates. They contribute to the formation and maintenance of the blood-brain barrier (notably astrocytes), participate in synaptic function and plasticity, and secrete neurotrophic factors that influence neuronal survival and growth. Oligodendrocytes form myelin sheaths around CNS axons, while Schwann cells perform myelination in the PNS. Microglia act as resident immune cells, surveying the nervous system and responding to injury or disease. Ependymal cells line the brain ventricles and contribute to cerebrospinal fluid production and movement, aided by cilia.

Clinical relevance: glial cells can give rise to tumors called gliomas, including astrocytomas, oligodendrogliomas, and glioblastoma. Glial dysfunction or loss of myelin is implicated in multiple sclerosis and various neuropathies, and glial responses contribute to neural repair and scar formation after injury.