Anatomy & Organs

Oligodendrocytes – structure, function & diseases

Oligodendrocytes

The oligodendrocytes belong to the group of glial cells and, along with the astrocytes and neurons , are an integral part of the central nervous system . As glial cells, they carry out supporting functions for the nerve cells. Some neurological diseases such as multiple sclerosis are caused by functional disorders of oligodendrocytes.

What are oligodendrocytes?

Oligodendrocytes are a special form of glial cells. In the central nervous system, they are responsible for the formation of myelin sheaths to insulate the nerve processes ( axons ). In the past, they were mainly assigned support functions similar to connective tissue .

In contrast to connective tissue, however, oligodendrocytes develop from the ectoderm. Today it is known that they have a great influence on the speed of information processing and on the energy supply of the neurons. In the peripheral nervous system , the Schwann cells assume functions similar to those of the oligodendrocytes in the CNS.

Oligodendrocytes are mainly found in the white matter. The white matter consists of axons surrounded by a myelin sheath. The myelin gives this region of the brain its white color. In contrast, the gray matter consists of the cell nuclei of the neurons. Since there are fewer axons here, the number of oligodendrocytes in the gray matter is also limited.

Anatomy & Structure

Oligodendrocytes are cells with small round nuclei. Their cell nuclei have a high content of heterochromatin, which can be easily detected using various staining techniques. Heterochromatin ensures that the genetic information in the oligodendrocytes usually remains inactive. In this way, the stability of these cells should be maintained in order to be able to perform their supporting function undisturbed.Oligodendrocytes have cell processes that produce myelin . With their extensions, they envelop the axons of the nerve cells and form myelin. With this myelin they wrap the nerve processes in a spiral. An insulating layer forms around the individual axons. An oligodendrocyte can produce up to 40 myelin sheaths that wrap around several axons. However, fewer processes emanate from the oligodendrocytes than from the other glial cells in the brain , the astrocytes.

The myelin consists largely of fats and to a lesser extent certain proteins . It is impermeable to electrical currents and therefore acts as a strong insulating layer. This separates the individual axons from each other. This layer of insulation looks similar to insulation around a cable. The insulating layer is missing at intervals of 0.2 to 1.5 millimeters.

These areas are called Ranvier’s nodes. Both isolation and the formation of isolated sections have great influence on the speed of information transfer.

Function & Tasks

The oligodendrocytes effectively insulate the individual nerve cell processes from one another with their myelin sheaths. In addition, at certain intervals in the myelin sheath, there are short, uninsulated areas known as nodes of Ranvier. In this way, the nerve signals can be transmitted more effectively and quickly.

The isolation of the axons already accelerates signal transmission. Dividing the insulation into sections makes this acceleration even more effective. The signal jumps from node to node. A speed of up to 200 meters per second or 720 km per hour can be generated. This high speed enables the development of a highly complex information processing. The same applies to the separate transmission through the isolation of the nerve cords. Without myelin sheaths, the axons would have to be very thick to achieve high signaling speeds.

It has already been calculated that without myelin sheaths, our optic nerve alone would have to be as thick as a tree trunk to perform the same work. In such complex organisms as vertebrates and especially humans, countless nerve impulses are transmitted, which have to be processed for information processing. Without oligodendrocytes, complex information processing and thus the development of intelligence would not be possible.

This function of oligodendrocytes has been known for decades. In recent years, however, there has been growing recognition that oligodendrocytes perform even more functions. For example, the axons are very long and the transmission of the signal also costs energy. However, the energy within the axons is not sufficient, especially since no replenishment comes from the cytoplasm of the neuron. According to the latest findings, the oligodendrocytes also absorb glucose and even store it as glucogen.

When there is an increased energy requirement in the axons, the glucose is first converted to lactic acid in the oligodendrocytes . The lactic acid molecules then travel down channels in the myelin sheath into the axon, where they provide energy for signal transmission.

Diseases

Oligodendrocytes play a major role in the development of neurological diseases such as multiple sclerosis. In multiple sclerosis, the myelin sheaths are destroyed, and the insulation of the axons is lost. The signals can no longer be forwarded correctly.It is an autoimmune disease in which the immune system attacks and destroys the body’s own oligodendrocytes. Multiple sclerosis often occurs in flares. After each attack, the body is stimulated to form new oligodendrocytes. The illness calms down. If the inflammation and thus the destruction of the oligodendrocytes become chronic, the nerve cells also die. Since these cannot regenerate, permanent damage occurs.

The question remains, however, why the neurons also perish. The discoveries made in recent years provide an answer. Oligodendrocytes supply energy to the neurons via the axons. When the energy supply ends, the nerve cells also die.

Website | + posts

Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.