Gliali

Gliali, commonly referred to as glial cells, are non-neuronal cells in the nervous system that provide support, protection, and maintenance for neurons. They are essential for the proper function of neural circuits, contributing to homeostasis, metabolism, and signaling environments.

In the central nervous system, the main glial cell types are astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes regulate the extracellular environment, participate in the blood-brain barrier, provide metabolic substrates, and modulate synaptic activity. Oligodendrocytes form myelin sheaths around CNS axons, increasing conduction velocity. Microglia act as resident immune cells, surveilling for injury and clearing debris; ependymal cells line ventricles and contribute to cerebrospinal fluid composition.

In the peripheral nervous system, Schwann cells myelinate peripheral axons, and satellite glial cells surround neuron bodies in ganglia to provide metabolic support and regulate the microenvironment.

Glial cells communicate with neurons through calcium signaling and gap junctions and participate in the concept of the tripartite synapse, in which astrocytes influence neurotransmitter dynamics and synaptic strength.

Developmentally, glial cells originate from neural tube progenitors and neural crest cells, with radial glia serving as developmental scaffolds for neurons and some glial lineages. In disease, glial responses include gliosis after injury and glial dysfunction has been implicated in conditions such as multiple sclerosis, amyotrophic lateral sclerosis, and various gliomas.

Markers used in research include GFAP for astrocytes, Iba1 for microglia, and Olig2 for oligodendrocyte lineage, among others.