Defining multipotent intermediate progenitors in cortical development

Cortical development is a tightly coordinated process driven by the self-renewal and differentiation of neural progenitors. Radial glia, the primary neuroectodermal progenitors of the cortex, generate diverse cortical cell types, in part through intermediate progenitors that amplify progenitor pools. Advances in single-cell profiling and lineage tracing have transformed the characterization and fate mapping of these intermediate progenitors. Notably, studies in mouse and human models have identified a new class of multipotent intermediate progenitors that generate cortical astrocytes, oligodendrocytes, and interneurons, broadening the classical view of glial-restricted progenitors. In this review, we synthesize emerging evidence for these intermediate progenitors, discuss the mechanisms underlying their specification, and propose an integrative framework for understanding their identity and role in cortical lineage specification.