Neural Stem Cells: are self-renewing, multipotent cells that firstly generate the radial glial progenitor cells that generate the neurons and glia of the nervous system of all animals during embryonic development. Some neural stem cells persist in highly restricted regions in the adult brain and continue to produce neurons throughout life. Stem cells are characterized by their capacity to differentiate into multiple cell types. There are two basic types of stem cell: adult stem cells, which are limited in their ability to differentiate, and embryonic stem cells (ESCs), which are pluripotent and have the capability of differentiating into any cell type.