Abstract: Glial proliferation: For the last decades, glial cells have been wrongly believed to have a mere passive supporting role for neurons. Nevertheless, this notion has clearly changed and it is now admitted that these cells are essential for the correct development and regulation of the nervous system. Glia cell population are commonly subdivided in astrocytes, oligodendrocytes and microglia. During the development, neural stem cells (NSCs) (called neuroepithelial progenitor cells or NPCs) transform into radial glia, the primary progenitor cells for neurons, astrocytes and oligodendrocytes (Zuchero and Barres, 2015). Microglial cells, however, derive from a mesenchymal precursor infiltration, meaning that during brain development, precursors generated in the bone narrow invade the nervous parenchyma and differentiate into microglial cells (Zuchero and Barres, 2015). This proliferative capacity is preserved in the adult mammalian brain, and neurogenic NSCs are stored in two restricted regions of the central nervous system (CNS), the forebrain subventricular zone (SVZ) and the hippocampal dentate gyrus (subgranular zone). These cells continue to produce neurons and glial cells during the adulthood, being activated after certain signals and leaving the quiescent state (Urbán et al., 2019). This process, in which glial progenitor cells differentiate into mature glia during development and in the adult brain to maintain and regulate brain function, is called gliogenesis (Ardaya et al., 2020). Besides these two niches, oligodendrocyte progenitor cells (OPCs) are present all around the CNS, both in the white and gray matter. These cells are the major dividing cells in the CNS generating new myelinating oligodendrocytes, or to a lesser extent astrocytes and they are constantly scanning the environment and controlling brain homeostasis. In addition, there is evidence of generation of new astrocytes from proliferating mature astrocytes in the brain parenchyma (Frisén, 2016). In summary, the capacity of generation of new glial cells is preserved not only in the SVZ and subgranular zone niches, but in the parenchymal tissue of the adult brain. In fact, the proliferative capacity of glial cells is increased in the injured CNS following neurological diseases. Adult OPCs play an important role in demyelinating diseases, where they turn to an activated state and start proliferating and migrating to the demyelination areas. Once there, they differentiate into mature oligodendrocytes and renew the destroyed myelin (Kuhn et al., 2019). After brain ischemia, microglia and astrocytes play an important role, representing the primary defense line facing neuroinflammation. Different studies using rodents have tried to disclose how microglia and astrocytes behave in this context and what triggers its activation. There is evidence of formation of a glial scar by reactive astrocytes originated from NSCs in the SVZ niche, but also generated through proliferation of local resident astrocytes (Nakafuku and Del Águila, 2020). Krishnasamy et al. (2017) showed the expression of nestin, a stem cell marker, in both reactive astrocytes and activated microglia after brain injury. These studies confirmed that glial cells differentiate and proliferate in order to restore the injured tissue, concluding that adult mammalian brain has the capacity of tissue repair following neuroinflammation.