A pioneer neuron is a cell that is a derivative of the preplate in the early stages of corticogenesis of the brain.
Pioneer neurons settle in the marginal zone of the cortex and project to sub-cortical levels.
In the rat cortex, they appear at embryonic day (E) 11.5 in the lateral aspect of the telencephalic vesicle and cover its whole surface on E12.
These cells, which show intense immunoreactivity for calbindin and calretinin, are characterized by their large size and axonal projection.
In many systems pioneer neurons are eliminated by programmed cell-death and are not present in the adult.