Transcriptional divergence of the zebrafish sox17 lineage begins during gastrulation

Although the gene regulatory network underlying endoderm specification and the later processes that regionalize the gut are increasingly well understood, comparatively little is known about the developmental interval separating these events.

Using single cell transcriptomics, we profiled the zebrafish sox17 lineage, comprising endoderm and dorsal forerunner cells, throughout and immediately after gastrulation. We found that dorsal forerunner cells remain transcriptionally homogeneous while undergoing coordinated temporal changes, associated with ciliogenesis and epithelial organization, during assembly of Kupffer's Vesicle. In contrast, endoderm cells transition from a migratory to an epithelial transcriptional state while progressively acquiring distinct regional identities.