Name: glial cells and nervous system support
Uploaded: 2025-10-23T11:49:28.000Z
Duration: 1 min 4 s
Channel: JoVE

Glial cells are the supporting cells in the nervous systems.

The central nervous system or CNS contains a variety of glia. The largest and most abundant type are astrocytes.These cells have many functions, one of which is to help to maintain the blood brain barrier.

Another kind, oligodendrocytes, with smaller cell bodies and fewer processes, forms the myelin sheaths along the length of axons.

The least numerous and smallest cells, microglia, are involved in phagocytic processes, engulfing pathogens and cellular debris.

In addition, the peripheral nervous system, or PNS includes satellite cells that surround neuron cell bodies and function like astrocytes found in the CNS. Similarly, schwann cells are the cells that act like oligodendrocytes, helping to form sheaths around peripheral axons. As research continues, it's clear that glial cells go beyond being simply glue in the nervous system.

As research continues, it's clear that glial cells go beyond being simply glue in the nervous system.

glial cells

<h4>Overview</h4>

Glial cells are one of the two main types of cells in the nervous system. Glia cells comprise astrocytes, oligodendrocytes, microglia, and ependymal cells in the central nervous system, and satellite and Schwann cells in the peripheral nervous system. These cells do not communicate via electrical signals like neurons do, but they contribute to virtually every other aspect of nervous system function. In humans, the number of glial cells is roughly equal to the number of neurons in the brain.

<h4>Glial Cells of the Central Nervous System</h4>

Glia in the central nervous system (CNS) include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most abundant type of glial cell and are found in organized, non-overlapping patterns throughout the brain, where they closely associate with neurons and capillaries. Astrocytes play numerous roles in brain function, including regulating blood flow and metabolic processes, synaptic ion and pH homeostasis, and blood-brain barrier maintenance.

Another specialized glial cell, the oligodendrocyte, forms the myelin sheath that surrounds neuronal axons in the CNS. Oligodendrocytes extend long cellular processes that wrap around axons multiple times to form this coating. Myelin sheath is required for proper conduction of neuronal signaling and greatly increases the speed at which these messages travel.

Microglia&#8212;known as the macrophages of the CNS&#8212;are the smallest glial cell type and specialize in phagocytosis of both pathogens and debris. They protect the CNS from infectious agents and toxins and prune synapses during development. Although microglia are considered glial cells, they have a unique and separate origin compared to other glial cell types. Astrocytes and oligodendrocytes are produced by radial glia, whereas microglia originate from the yolk sac and migrate into the embryo early in embryonic development.

Lastly, ependymal cells are cube-shaped cells with cilia-like protrusions that line the ventricles, where they produce cerebrospinal fluid (CSF). Ependymal cells form a barrier between the brain and the CSF, filtering out potentially harmful substances. Like astrocytes and oligodendrocytes, ependymal cells originate from radial glia found near the lateral ventricles.

<h4>Glial Cells of the Peripheral Nervous System</h4>

In the peripheral nervous system (PNS), similar yet distinct types of glial cells exist. For example, functions performed by CNS astrocytes are accomplished in the PNS primarily by satellite cells, glial cells that provide structure, cushioning, and nutrients to the neuronal bodies they associate with. Another PNS glial cell, the Schwann cell, functions like CNS oligodendrocytes by forming a myelin sheath around neuronal axons. Like myelination in the CNS, PNS axon myelination provides necessary insulation and conductivity for the proper transmission of electrical signals.

<h4>Importance of Glia in Health and Disease</h4>

Glial cells are critical nervous system protectors and regulators. Not only do they maintain homeostatic conditions and contribute to routine brain function, but they also respond to nervous system injury, infection, and disease. In addition, glia perform critical functions during embryonic development of the nervous system. These cells even contribute to the removal of unnecessary neuronal connections, a process called synaptic pruning. Due to the importance of glia in numerous aspects of brain function, defects in one or more glial cell populations can lead to severe and debilitating neurological conditions, including developmental disorders, Alzheimer&#8217;s disease, Parkinson&#8217;s disease, multiple sclerosis, and many others.

During development, glial cells provide a scaffolding for neurons to properly migrate on and grow out their axons. Later in life, trauma or neurodegenerative diseases can cause loss of neuronal connections that cannot be regenerated, leading to impaired functioning or paralysis.

Glial Cells

Overview

Glial cells are one of the two main types of cells in the nervous system. Glia cells comprise astrocytes, oligodendrocytes, microglia, and ...

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KEY TERMS AND CONCEPTS

glial cells and nervous system support

Glial cells support the nervous system and work alongside neurons. They are one of the two main cell types in the nervous system. Unlike neurons, glia do not send electrical signals, but they help with nearly every other part of nervous system function. In humans, glial cells are about as numerous as neurons in the brain.

In the central nervous system, glia include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most common glial cells. They form organized, non-overlapping patterns in the brain and stay close to neurons and capillaries. They help regulate blood flow, support metabolism, maintain ion and pH balance around synapses, and help maintain the blood-brain barrier.

Oligodendrocytes make the myelin sheath in the central nervous system. This sheath wraps around neuronal axons many times and acts as insulation. Myelin helps nerve signals travel correctly and much faster. Microglia are the smallest glial cells and are known as the macrophages of the CNS. They remove pathogens and debris by phagocytosis and also help prune synapses during development. Unlike other glia, microglia come from the yolk sac and enter the embryo early in development.

Ependymal cells are cube-shaped cells with cilia-like projections that line the ventricles. They produce cerebrospinal fluid, or CSF, and form a barrier between the brain and the CSF. This barrier helps filter out harmful substances. Like astrocytes and oligodendrocytes, ependymal cells come from radial glia near the lateral ventricles.

The peripheral nervous system also has glial cells. Satellite cells support the neuronal cell bodies they surround by providing structure, cushioning, and nutrients. Schwann cells do for peripheral axons what oligodendrocytes do in the CNS. They form myelin around axons and help insulation and conductivity for electrical signaling.

Glia are important for health, development, and disease. They protect the nervous system, keep internal conditions stable, and respond to injury, infection, and disease. They also help guide neuron migration and axon growth during embryonic development. Because they help remove extra neuronal connections through synaptic pruning, problems in glial cells can contribute to developmental disorders, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and other serious conditions. Damage later in life can also lead to lost connections that are difficult or impossible to replace, which may cause impaired function or paralysis.

Glial Cells and Nervous System Support

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Glial cells support the nervous system and work alongside neurons. They are one of the two main cell types in the nervous system. Unlike neurons, glia do not send electrical signals, but they help with nearly every other part of nervous system function. In humans, glial cells are about as numerous as neurons in the brain. In the central nervous system, glia include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most common glial cells. They form organized,...

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key terms and concepts

Learn how astrocytes, oligodendrocytes, microglia, ependymal cells, satellite cells, and Schwann cells support neurons in the CNS and PNS.

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Glial Cells and Nervous System Support

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