A pioneer neuron is a cell that is a derivative of the preplate in the early stages of

corticogenesis The development of the cerebral cortex, known as corticogenesis is the process during which the cerebral cortex of the brain is formed as part of the development of the nervous system of mammals including development of the nervous system in humans ...

of the brain. Pioneer neurons settle in the marginal zone of the cortex and project to sub-cortical levels. In the rat, pioneer neurons are only present in prenatal brains. Unlike Cajal-Retzius cells, these neurons are

reelin Reelin, encoded by the ''RELN'' gene, is a large secreted extracellular matrix glycoprotein that helps regulate processes of neuronal migration and positioning in the developing brain by controlling cell–cell interactions. Besides this importa ...

-negative. Pioneer neurons are born in the ventricular neuroepithelium all over the cortical

primordium A primordium (; : primordia; synonym: anlage), in embryology, is an Organ (anatomy), organ or tissue in its earliest recognizable stage of development. Cell (biology), Cells of the primordium are called primordial cells. A primordium is the simp ...

. 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 Calbindins are three different calcium-binding proteins: calbindin 1, calbindin, calretinin and S100G. They were originally described as vitamin D-dependent calcium-binding proteins in the intestine and kidney of chicks and mammals. They are now ...

and

calretinin Calretinin, also known as calbindin 2 (formerly 29 kDa calbindin), is a calcium-binding protein involved in calcium signaling. In humans, the calretinin protein is encoded by the ''CALB2'' gene. Function This gene encodes an intracellular ...

, are characterized by their large size and axonal projection. They remain in the marginal zone after the formation of the cortical plate; they project first into the ventricular zone, and then into the

subplate The subplate, also called the subplate zone, together with the marginal zone and the cortical plate, in the fetus represents the developmental anlage of the mammalian cerebral cortex. It was first described, as a separate transient fetal zon ...

and the

internal capsule The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...

. Therefore, these cells are the origin of the earliest efferent pathway of the developing cortex.

Function

It is thought that axons of pioneer neurons, pioneer axons, serve as a pathway for additional neurons that develop later in the embryo and project their axons to the appropriate target. In many systems pioneer neurons are eliminated by programmed cell-death and are not present in the adult.

External links

*
Neuronal Migration and Formation of Cellular Patterns During Brain Development
- from the site of the University of Texas. * {{cite journal , vauthors=Meyer G, Goffinet AM, Fairén A , title=What is a Cajal-Retzius cell? A reassessment of a classical cell type based on recent observations in the developing neocortex , journal=Cereb. Cortex , volume=9 , issue=8 , pages=765–75 , date=December 1999 , pmid=10600995 , doi=10.1093/cercor/9.8.765 , doi-access=free Authors of the article propose new criteria to distinguish between different cell types in the developing cortex. Developmental neuroscience

Function

See also

External links