Simulation of the cortical plate formation.
Slice view exported from the CX3D simulator; for clarity the subplate cells have been removed. (A) After formation of the preplate, the cells in the ventricular zone (VZ) either form radial glial cells (black cells) extending a radial glial process (RGP), or stay in proliferative mode, increasing the precursor pool of the VZ (turquoise). (B) When the first neuron precursors (blue) are formed in the VZ, they migrate by climbing along the RGP toward their final position, forming the future layer 6. Once the neuron precursors detect a contact with either the top-most L1 cells (yellow) or with cells of their own kind, they stop their migration by detaching from the radial fibers. (C) When L5 cells (magenta) are formed they migrate through the L6 cells (some of which are still being produced) and stop just below L1; at the same time the second pool of precursors is formed in the subventricular zone (grey). (D,E) L4 (red) and then L23 cells (green) are produced in the SVZ, and migrate toward L1. L1 cells are physically pushed upward by the neuron precursors, which displaces the stopping signal. (F) In the final laminated structure, there is no VZ or SVZ anymore. The somata start to secrete a diffusible, cell type specific guidance cue in order to guide the axonal and dendritic outgrowth.