This review highlights how novel cutting-edge technologies, including high-resolution imaging, single-cell omics, and organoid cultures, have improved our understanding of human thymus biology, in terms of developmental trajectories, cellular heterogeneity, and spatial organization.

Multipotent blood progenitors begin T cell development in the thymus, activating a multistep gene regulatory network. This review explores how the dynamic interplay between Notch signals, Notch-induced factors, and progenitor-associated factors control T-development progression by synergizing and opposing each other’s action.

TCR rearrangement endows the preselection thymocyte repertoire with wide-ranging ligand specificity. Here, we discuss how thymic selection matures or eliminates clonotypes with particular specificities and develops T cell sublineages and microrepertoires according to their antigen-recognition capabilities.