 As described, the increasing dose of radiation and age led to decrease in three cell types of the SVZ, yet repair capacity of the SVZ was observed despite the lack of white matter necrosis; this occurred likely because the SVZ was able to gradually replace the neuroglia of the brain.Chemotherapeutics were also tested for their effects on the SVZ, as they are currently used for many diseases yet lead to complications within the central nervous system.To do so, methotrexate (MTX) was used alone and in combination with radiation to find that roughly 70% of the total nuclear density of the SVZ had been depleted, yet given loss of neuroblast cells (progenitor cells), it was remarkable to find that SVZ NSCs would still generate neurospheres similar to subjects that did not receive such treatment.