During embryonic development in bilaterally symmetric organisms, correct midline crossing is important for the proper formation of functional neural circuits. The aberrant development of neural circuits can result in multiple neurodevelopmental disorders, including horizontal gaze palsy, congenital mirror movement disorder, and autism spectrum disorder. Thus, understanding the molecular mechanisms that regulate proper axon guidance at the midline can provide insights into the pathology of neurological disorders. The signaling mechanisms that regulate midline crossing have been extensively studied in the Drosophila ventral nerve cord and the mouse embryonic spinal cord. In this review, we discuss these axon guidance mechanisms, highlighting the most recent advances in the understanding of how commissural axons switch their responsiveness from attractants to repellents during midline crossing.

在双边对称生物的胚胎发育过程中，正确的中线交叉对于功能性神经回路的正确形成很重要。神经回路的异常发育可导致多种神经发育障碍，包括水平凝视麻痹、先天性镜像运动障碍和自闭症谱系障碍。因此，了解在中线调节适当轴突引导的分子机制可以提供对神经系统疾病病理学的见解。在果蝇中广泛研究了调节中线交叉的信号机制腹神经索和小鼠胚胎脊髓。在这篇综述中，我们讨论了这些轴突引导机制，重点介绍了在中线交叉期间连合轴突如何将其响应性从引诱剂转换为驱避剂的最新进展。