In vertebrates, a<unk>  or primitive nerve cell is a postmitotic cell that does not divide further, and which will develop into a neuron after a migration phase. In invertebrates such as Drosophila,<unk> s are neural progenitor cells which divide asymmetrically to produce a<unk> , and a daughter cell of varying potency depending on the type of<unk> . Vertebrate<unk> s differentiate from radial glial cells and are committed to becoming neurons. Neural stem cells, which only divide symmetrically to produce more neural stem cells, transition gradually into radial glial cells. Radial glial cells, also called radial glial progenitor cells, divide asymmetrically to produce a<unk>  and another radial glial cell that will re-enter the cell cycle. This mitosis occurs in the germinal neuroepithelium (or germinal zone), when a radial glial cell divides to produce the<unk> . The<unk>  detaches from the epithelium and migrates while the radial glial progenitor cell produced stays in the lumenal epithelium. The migrating cell will not divide further and this is called the neuron's birthday. Cells with the earliest birthdays will only migrate a short distance. Those cells with later birthdays will migrate further to the more outer regions of the cerebral cortex. The positions that the migrated cells occupy will determine their neuronal differentiation.
Neuroblast
Keratinocyte
Trophoblast
Nurse cell
Elliptocyte
Echinocyte
Koilocyte
Melanocyte