Cell polarity is defined as the asymmetric distribution of cellular components along an axis. Most cells, from the simplest single-cell organisms to highly specialized mammalian cells, are polarized and use similar mechanisms to generate and maintain polarity. Cell polarity is important for cells to migrate, form tissues, and coordinate activities. During development of the mammalian cerebral cortex, cell polarity is essential for neurogenesis and for the migration of newborn but as-yet undifferentiated neurons. These oriented migrations include both the radial migration of excitatory projection neurons and the tangential migration of inhibitory interneurons. In this review, I will first describe the development of the cerebral cortex, as revealed at the cellular level. I will then define the core molecular mechanisms – the Par/Crb/Scrib polarity complexes, small GTPases, the actin and microtubule cytoskeletons, and phosphoinositides/PI3K signaling – that are required for asymmetric cell division, apico-basal and front-rear polarity in model systems, including C elegans zygote, Drosophila embryos and cultured mammalian cells. As I go through each core mechanism I will explain what is known about its importance in radial and tangential migration in the developing mammalian cerebral cortex.

细胞极性定义为细胞成分沿轴的不对称分布。从最简单的单细胞生物到高度专业化的哺乳动物细胞，大多数细胞都是极化的，并使用类似的机制产生和维持极性。细胞极性对于细胞迁移，形成组织和协调活动至关重要。在哺乳动物大脑皮层的发育过程中，细胞极性对于神经发生以及新生但尚未分化的神经元的迁移至关重要。这些定向的迁移既包括兴奋性投射神经元的径向迁移，也包括抑制性中间神经元的切向迁移。在这篇综述中，我将首先描述在细胞水平上揭示的大脑皮层的发育。秀丽隐杆线虫合子，果蝇胚胎和培养的哺乳动物细胞。当我研究每种核心机制时，我将解释其在发展中的哺乳动物大脑皮层中的径向和切向迁移中的重要性的已知知识。