Spatiotemporal dynamics of neuron differentiation and migration in the developing human spinal cord.

Precise formation of complex neural circuits in the spinal cord, achieved through the integration of diverse neuronal populations, is essential for central nervous system function. However, the specialization and migration of human spinal cord neurons remain poorly understood. In this study, we perform single-cell transcriptome sequencing of human spinal cord from Carnegie Stages (CS) 16-21 and mouse spinal cord from embryonic day (E) 8.0-11.5, complemented by in situ sequencing of human spinal cord (CS 16-20). Our results reveal the critical role of the precursor state in neuronal differentiation and migration, identifying key transcription factors that regulate these processes across species. Notably, each neuronal lineage expresses unique markers as early as the progenitor stage at the spinal cord midline, and subsequently undergoes a shared transcriptional program during precursor commitment that guides migration. This synchronized migration, validated by spatial transcriptomics, occurs in both dorsal and ventral regions. Our findings offer important insights into the migration patterns and regulatory factors that guide spinal cord neuron subtype specification during embryogenesis.