Nowakowski Tomasz J, Pollen Alex A, Sandoval-Espinosa Carmen, Kriegstein Arnold R
Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA.
Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA.
Neuron. 2016 Sep 21;91(6):1219-1227. doi: 10.1016/j.neuron.2016.09.005.
The classic view of cortical development, embodied in the radial unit hypothesis, highlights the ventricular radial glia (vRG) scaffold as a key architectonic feature of the developing neocortex. The scaffold includes continuous fibers spanning the thickness of the developing cortex during neurogenesis across mammals. However, we find that in humans, the scaffold transforms into a physically discontinuous structure during the transition from infragranular to supragranular neuron production. As a consequence of this transformation, supragranular layer neurons arrive at their terminal positions in the cortical plate along outer radial glia (oRG) cell fibers. In parallel, the radial glia that contact the ventricle develop distinct gene expression profile and "truncated" morphology. We propose a supragranular layer expansion hypothesis that posits a deterministic role of oRG cells in the radial and tangential expansion of supragranular layers in primates, with implications for patterns of neuronal migration, area patterning, and cortical folding.
径向单元假说所体现的皮质发育经典观点强调，脑室径向胶质细胞（vRG）支架是发育中的新皮质的关键结构特征。在整个哺乳动物的神经发生过程中，该支架包括贯穿发育中皮质厚度的连续纤维。然而，我们发现，在人类中，在从颗粒下层神经元产生向颗粒上层神经元产生的转变过程中，该支架转变为物理上不连续的结构。这种转变的结果是，颗粒上层神经元沿着外侧径向胶质细胞（oRG）纤维到达它们在皮质板中的终末位置。同时，与脑室接触的径向胶质细胞发展出独特的基因表达谱和“截断”形态。我们提出了一个颗粒上层扩展假说，该假说认为oRG细胞在灵长类动物颗粒上层的径向和切向扩展中起决定性作用，这对神经元迁移模式、区域模式形成和皮质折叠具有重要意义。
