Thinking about the brain or nervous system in general is equivalent to thinking about neurons. The neuron is the basic unit of the nervous system, which is why we usually focus on them when we are exploring the functioning of the nervous system. But there are not only neurons in the brain. We can also find glial cells, which sustain, protect and keep the neurons alive. Among the many types of glial cells that we can find, in this article we will focus on the so-called radial glia , an essential element for our development.

What are glial cells?

We understand glial cells to be a group of cells derived from the embryonic epithelium that cover the nervous system and form a network of support, protection, nutrition and maintenance of the neurons. Initially it was believed that they were a substance that only held neurons together, although this hypothesis was rejected after the discovery of the existence of synapses.

Its functions are multiple: besides contributing to give a structure to the nervous system, it has been observed that glial cells are the ones that put in interaction the neurons with the cells of the cerebrovascular system, acting as a filter. This means that glia can provide nutrients and oxygen to neurons , which refers to one of its main and most important roles: to provide nutrients and keep the nervous system alive. A final and especially relevant role of this type of cell is the fact that they eliminate waste and maintain stability in the environment in which the neurons are located.

But although traditionally they were considered mainly to be supportive, recent research proposes that they are capable of both capturing and releasing information-transmitting substances with a possible influence on the synaptic transmission that occurs between neurons. Thus, they have an effect on information processing beyond mere neuronal support.

Glial cells are essential for the proper functioning and survival of the nervous system. But the term glial includes a large number of cell types. Among them we can find astrocytes, oligodendrocytes, the Schwann cells or the one we are dealing with in this article, the radial glia.

Radial glia: basics

With regard to the radial glia, we are dealing with a type of glial cell with a generally bipolar morphology that extends throughout the cerebral and cerebellar cortex (although in the latter case there are more elongations, being multipolar). These are cells that serve as structural pillars and contribute to the development of the nervous system.

They have often been linked to another type of glial cell, astrocytes, because they play roles typical of this type of glial cell and, like them, they have similar cytoskeleton and membrane proteins (possessing among other receptors glutamate or GABA). In fact, radial glia can be converted or derived into these.

The radial glia, also called aldainogly, is primarily known to serve as a pathway or guide for neurons during fetal development . This guidance is produced by the interaction of glia and neuron, through a process of chemical attraction and the role of glia in promoting the growth and migration of nerve fibers.

However, that role is reduced over time: once the migration of the cortex neurons to their final position has taken place and new neurons are no longer born in most areas of the nervous system, their role becomes focused on supporting the neural network.

Its most important and well-known functions

The radial glia plays different roles within the body, but the most prominent, researched and known of them all we have mentioned above: it is the type of cell that allows and acts as a guide for neurons during neuronal migration , allowing them to reach the positions that pertain to them.

This process is especially visible during fetal development, as newly formed neurons travel through the glial cells, using them as a guide to the cortex. Although this is not the only method of neuronal migration available, it is the best known and most widely used, especially with regard to the cerebral cortex.

In addition to this guidance and transport function, radial glia has also been linked to the generation and synthesis of neurons : it has been observed that they can act as progenitors of other cells such as neurons. This neurogenesis is especially linked to childhood, but its involvement in the birth of new nerve cells in the adult brain is suspected in the few areas where it has been detected (in the hippocampus and the olfactory bulb is where it has been most observed). They have also been associated with the recovery of some functions after the presence of brain injuries, and their link to processes such as synaptic and neuronal pruning that occur during growth has been observed.

It has been seen that glial cells also play a very important role in generating a complex, functional and stable cerebrovascular network in the brain, especially in the early stages of life but also throughout the life cycle. In experiments with mice it was observed that their inhibition generates a degradation of the cerebral vascularization network and the brain’s metabolism, something that greatly facilitates the appearance of neurodegeneration (something that is in fact discussed about its involvement in diseases such as Alzheimer’s).

Finally, it is worth mentioning that like the rest of glial cells, radial glia also has an important role in supporting and keeping alive the neurons that surround them, facilitating their growth and nourishing them.

Bibliographic references

  • Glial cells are essential for the proper functioning and survival of the nervous system. But the term glial includes a large number of cell types. Among them we can find astrocytes, oligodendrocytes, the Schwann cells or the one we are dealing with in this article, the radial glia.

    Radial glia: basics

    With regard to the radial glia, we are dealing with a type of glial cell with a generally bipolar morphology that extends throughout the cerebral and cerebellar cortex (although in the latter case there are more elongations, being multipolar). These are cells that serve as structural pillars and contribute to the development of the nervous system.

    They have often been linked to another type of glial cell, astrocytes, because they play roles typical of this type of glial cell and, like them, they have similar cytoskeleton and membrane proteins (possessing among other receptors glutamate or GABA).
    In fact, radial glia can be converted or derived into these.

    The radial glia, also called aldainogly, is primarily known to serve as a pathway or guide for neurons during fetal development .
    This guidance is produced by the interaction of glia and neuron, through a process of chemical attraction and the role of glia in promoting the growth and migration of nerve fibers.