The nervous system consists of neurons and glial cells. Neurons generate and propagate electrical and chemical signals, whereas glia function. Despite the essential function of neurons, about 90% of the cells in the CNS are glia. Glia were originally believed to be passive cells that only acted physically. The glial cells surround neurons and provide support for and insulation between them. Glial cells are the most abundant cell types in the central nervous system. Types of glial cells include oligodendrocytes, astrocytes, ependymal cells, Schwann cells, microglia, and satellite cells.


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Neurons are glial cells function in yellow, with the blue of oligodendrocytes forming the myelin sheath around the axon. Ependymal cells line the spinal cord and ventricles of the brain. They are involved in creating cerebrospinal fluid CSF.

Radial glial cells are progenitor cells that can generate neurons, astrocytes and oligodendrocytes. Peripheral Nervous System Schwann cells: Others regulate the internal environment of the brain, especially the fluid surrounding neurons and their synapsesand nutrify neurons.

During early glial cells functionglial cells direct the migration of neurons and produce molecules that modify the growth of axons and dendrites. Neuron repair and development[ edit ] Glia are also crucial in the development of the nervous glial cells function and in processes such as synaptic plasticity and synaptogenesis.

Glia have a role in the regulation of repair of neurons after injury.

Glia functions in the CNS | Abcam

In the central nervous system CNSglia suppress repair. Glial cells known as astrocytes enlarge and proliferate to form a scar and produce inhibitory molecules that inhibit regrowth of a glial cells function or severed axon. In the peripheral nervous system PNSglial cells known as Schwann cells promote repair.

After axonal injury, Schwann cells regress to an earlier developmental state to encourage regrowth of the axon. For example, a spinal cord may be able to be repaired following injury or severance.

Schwann cells are also known as neuri-lemmocytes.

All 3 types of glial cells are important for memory formation | Frontiers Research Topic

These cells envelop nerve fibers of the PNS by winding repeatedly around a nerve fiber with the nucleus inside of it. This process creates a myelin sheath, which not only aids in conductivity but also assists in the regeneration of glial cells function fibers.

Myelin sheath creation[ edit ] Oligodendrocytes are another type of glial cell of the CNS. These dendrocytes resemble an octopus bulbous body and contain up to fifteen arm-like processes.

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To specifically target and subsequently ablate cycling cells, the application of high doses of X-irradiation Kalderon and Fuks, ; Chari and Blakemore, or of the mitotic blocker arabinofuranosyl cytidine AraC, Doetsch et al.

These general ablation approaches, which are still in use today, glial cells function likely favored due to the simplicity of application and due to the lack of more specific alternatives.

X-irradiation as well as the application of AraC is not cell glial cells function specific, as all cycling cells in the area X-irradiation or tissue AraC of interest undergo induced cell death.

Therefore these approaches are not ideal to identify the function of a specific cell type.

Glial Cells and Their Function in the Adult Brain: A Journey through the History of Their Ablation

The use of such general approaches has decreased, as drugs can have effects in other tissues that lead to secondary damage or even changes in glial cells function cells of interest.

As genetic manipulation has become easier and more accessible within the recent years, cell ablation techniques have also improved. Suicide genes typically encode either a toxin, an enzyme that converts a pro-drug into a toxic agent, or an essential protein for the specific cell type leading to apoptotic cell death specifically in the cells of interest.

The main advantage of these approaches is that they have few side effects for surrounding cells or other tissues. Application of these ablation methods have already helped us to better understand the functions of all four major glial cell types in the adult brain.

This review will summarize and discuss the major findings of ablation studies performed during the last few decades.


Microglia Microglia Ablation under Healthy Conditions In a very simplified view, microglia are the immunocompetent and phagocytic cells of the nervous system.