Feeling at home: Identifying a human thymic epithelial progenitor cell niche.

T cell development relies on a supportive epithelial microenvironment. Embryonic and postnatal epithelial progenitors have been identified in mice, but not humans. In this issue of Developmental Cell, Raggazzini et al. use scRNAseq, spatial sequencing, and clonogenic assays to identify a putative bipotent TEPC in pediatric human thymic tissue.