Induction of embryonic axes by distinct population of the Hensens's node [scRNAseq]

The vertebrate body plan is established during gastrulation through the activity of the organizer, a specialized group of cells that harbors the ability to instruct fate and morphogenesis in the early embryo. In Xenopus, the organizer is segregated into head and trunk subpopulations, which promote the patterning of the embryonic antero-posterior axis. Here we profiled the avian organizer populations located in the Hensen's node using single-cell RNA-seq. Our results reveal that the chick organizer is composed of two distinct populations expressing factors known to regulate the formation of head structures and posterior mesoderm. Mapping of trajectory analysis and RNA-velocity of the Hensen's node in different embryonic stages indicate that the segregation into head and trunk subpopulations occurs at late gastrula stage HH4. The trunk population induces the formation of notochord and somites when ectopically grafted into a host embryo. Overall design: Examination of transcriptome of single cells from chick embryos at stages HH3, HH4 and HH6