Gliale

Gliale, often referred to as glia, denotes a family of non-neuronal cells in the nervous system that support and protect neurons. They are essential for maintaining the environment around neurons, modulating synaptic activity, and contributing to brain structure. In many species, glial cells outnumber neurons and occupy a substantial portion of nervous tissue.

In the central nervous system, major glial types include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes regulate blood flow and the blood-brain barrier, supply metabolic support, and help clear excess neurotransmitters. Oligodendrocytes form myelin sheaths around axons, increasing conduction speed. Microglia act as resident immune cells, surveying and responding to injury. Ependymal cells line ventricular cavities and participate in cerebrospinal fluid production and movement. In the peripheral nervous system, Schwann cells myelinate peripheral axons, and satellite cells provide metabolic and nutritional support for neurons in ganglia. During development, radial glia serve as scaffolds for migrating neurons, and some glia arise from these progenitors.

Glial biology is central to both normal nervous system function and disease. Glial dysfunction or activation is implicated in a range of conditions, including demyelinating diseases such as multiple sclerosis, where myelin-producing glia are damaged; neuroinflammation and neurodegeneration; and glial-derived tumors such as astrocytomas and oligodendrogliomas.