The emergent landscape of the mouse gut endoderm at single-cell resolution

To comprehensively delineate the ontogeny of an organ system, we generated 112,217 single- cell transcriptomes representing all endoderm populations within the mouse embryo until midgestation. We employed graph-based approaches to model differentiating cells for spatio- temporal characterization of developmental trajectories. Our analysis reveals the detailed architecture of the emergence of the first (primitive or extra-embryonic) endodermal population and pluripotent epiblast. We uncover an unappreciated relationship between descendants of these lineages, before the onset of gastrulation, suggesting that mixing of extra-embryonic and embryonic endoderm cells occurs more than once during mammalian development. We map the trajectories of endoderm cells as they acquire embryonic versus extra-embryonic fates, and their spatial convergence within the gut endoderm; revealing them to be globally similar but retaining aspects of their lineage history. We observe the regionalized localization of cells along the forming gut tube, reflecting their extra-embryonic or embryonic origin, and their coordinate patterning into organ-specific territories along the anterior-posterior axis. Overall design: Total RNA was extracted from bulk tissue and dissociated cells of 13ss (~E8.75) gut tubes, from bulk tissue from anterior, anterior-midgut, midgut-posterior and posterior sections of 13ss gut tubes, as well as from extra-embryonic visceral endoderm and embryonic visceral endoderm of E7.5 embryos (see also table in section: Bulk RNA processing). The Trizol method (Invitrogen) was used for RNA extraction.

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Nowotschin S, Setty M, Kuo YY, Liu V, Garg V, Sharma R, Simon CS, Saiz N, Gardner R, Boutet SC, Church DM, Hoodless PA, Hadjantonakis AK, Pe'er D