Thinking of the brain or the nervous system in general is like thinking of neurons. And is that the neuron is the basic unit of the nervous system, which is why we usually focus on them when we explore how this system works. But in the brain, it’s not just neurons. We can also find glial cells, which support, protect, and keep 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?
By glial or glial cells, we mean the set of cells derived from the embryonic epithelium that cover the nervous system and form a network of support, protection, nutrition and maintenance of neurons. They were initially thought to be a substance that only held neurons together, although this hypothesis was rejected after the discovery of the existence of synapses.
Its functions are numerous: in addition to helping to structure the nervous system, it has been observed that it is the glial cells that interact with the neurons of the cells of the cerebrovascular system, acting as a filter. This means that the glia can supply nutrients and oxygen to neurons., Which refers to one of its main and most important roles: providing nutrients and keeping the nervous system alive. A final particularly important role of this type of cell is that they remove waste and maintain stability in the environment in which neurons are located.
But although they have traditionally been viewed primarily as supports, recent research suggests that they are capable of both capturing and releasing information-carrying substances with a possible influence on synaptic transmission that occurs between neurons. Thus, they have an effect on the processing of information beyond the simple neural support.
Glial cells are essential for the proper functioning and survival of the nervous system. But the term glia includes a large number of cell types. Among them we can find astrocytes, oligodendrocytes, Schwann cells or the one we are talking about in this article, radial glia.
Radial glia: basic elements
As for the radial glia, we are in front 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 a structural pillar 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 possess cytoskeletal and cytoskeletal proteins. Similar membrane (having among others glutamate or GABA receptors). In fact, radial glia can become or drift into these.
The radial glia, also called aldainoglía, is known primarily to serve as pathway or guide for neurons during fetal development. This guide occurs due to the interaction of the glia and the neuron, through a process of attraction at the chemical level and the role of glia in promoting the growth and migration of nerve fibers.
However, this role is reduced over time: once the migration of neurons from the cortex to its final position occurs and once new neurons are born in most areas of the nervous system, its role shifts to focus. on neural network support.
Its most important and well-known functions
Radial glia plays different roles in the body, but the most important, studied and known to all, we have already mentioned above: it is the type of cell that enables and acts as a guide for neurons during neuronal migration, Allow them to reach the positions that belong to them.
This process is especially noticeable during fetal development, as the newly formed neurons pass 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 the most common, especially with regard to the cerebral cortex.
In addition to this guiding and transport function, the radial glia it has also been linked to neuronal generation and synthesis itself: It has been observed that they can act as progenitors of other cells such as neurons. This neurogenesis is mainly 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 in the olfactory bulb, it is there. that we observed the most). They have also been linked to the recovery of certain functions after the presence of brain damage, and their link with processes such as synaptic and neuronal pruning that occur during growth has been observed.
Glial cells have also been shown to have a very important role in the generation of a complex cerebrovascular network, Functional and stable in the brain, especially early in life but also throughout the life cycle. In experiments with mice, its inhibition has been observed to generate degradation of the cerebral vascular network and brain metabolism, which greatly facilitates the onset of neurodegeneration (which is in fact debated for its involvement in diseases such than Alzheimer’s disease).
Finally, it should be mentioned that, like other glial cells, radial glia also plays an important role in maintaining and keeping the neurons around them alive, facilitating their growth and nourishment.
- Allen, NJ and BA Bars (2009). Glia: more than just a cerebral tail. Nature, 457: 675-677.
- Malatesta, P. and Götz, M. (2013). Radial glia: from annoying cables to stem cell stars. Developments, 140: 483-486. The Society of Biologists Ltd.
- Rakic, P. (1972). Mode of cell migration in the superficial layers of the neocortex of the fetal monkey. Journal of Comparative Neurology, 145: 61-83.