The roles of morphogen during the development of dentate gyrus

哺乳动物大脑皮层的正常形态发生需要在适当的发育时期协调适当数量的细胞的增殖和分化。研究表明，神经干细胞（放射状胶质细胞：RGs）和神经前体细胞（中间祖细胞：IPC）位于发育中的端脑背侧。特别是，IPC在大脑皮层层II和III的分层中具有重要作用。我们先前报道了端脑背侧中的Hedgehog（Hh）信号传导维持RG和IPC的增殖、存活和分化（Komada等人，2008年）。本研究的结果表明，Hh信号控制细胞周期的长度和调节从RG到IPC或神经元和从IPC到神经元在胚胎第16天的过渡。5小鼠在灵长类动物的大脑皮层中，第二层和第三层高度发达，这些层是由IPC产生的神经元产生的。阐明这一机制可能有助于更好地理解高级脑功能的构成和精神障碍的发病机制。

Normal morphogenesis of the mammalian cerebral cortex requires orchestration of the proliferation and differentiation of the appropriate number of cells at the appropriate developmental period. Several lines of studies demonstrated that neural stem cells(radial glias : RGs) and neural precursor cells(Intermediate progenitor cells : IPCs) locate in the developing dorsal telencephalon. In particular, IPCs have important roles in the lamination of cerebral cortex layers II and III. We previously reported that Hedgehog(Hh) signaling in the dorsal telencephalon maintains the proliferat ion, survival, and differentiation of RGs and IPCs(Komada et al., 2008). The findings of the present study suggest that Hh signaling controls cell cycle length and regulates the transition from RG to IPCs or neurons and from IPCs to neurons at embryonic day 16. 5 in mice. In the primate cerebral cortex, layers II and III are highly developed and these layers are generated from neurons produced from IPCs. Elucidation of this mechanism is likely to contribute to a better understanding of the constitution of higher brain functions and the pathogenesis of mental disorders.