Visceral organs, such as the lungs, stomach and liver, are derived from the fetal foregut through a series of inductive interactions between the definitive endoderm (DE) and the surrounding splanchnic mesoderm (SM). While DE patterning is fairly well studied, the paracrine signaling controlling SM regionalization and how this is coordinated with epithelial identity is obscure. Here, we use single cell transcriptomics to generate a high-resolution cell state map of the embryonic mouse foregut. This identifies a diversity of SM cell types that develop in close register with the organ-specific epithelium. We infer a spatiotemporal signaling network of endoderm-mesoderm interactions that orchestrate foregut organogenesis. We validate key predictions with mouse genetics, showing the importance of endodermderived signals in mesoderm patterning. Finally, leveraging these signaling interactions, we generate different SM subtypes from human pluripotent stem cells (hPSCs), which previously have been elusive. The single cell data can be explored at: https://research.cchmc.org/ ZornLab-singlecell.

Tube morphogenesis is essential for internal-organ development, yet the mechanisms regulating tube shape remain unknown. Here, we show that different mechanisms regulate the length and diameter of the murine trachea. First, we found that trachea development progresses via sequential elongation and expansion processes. This starts with a synchronized radial polarization of smooth muscle (SM) progenitor cells with inward Golgi-apparatus displacement regulates tube elongation, controlled by mesenchymal Wnt5a-Ror2 signaling. This radial polarization directs SM progenitor cell migration toward the epithelium, and the resulting subepithelial morphogenesis supports tube elongation to the anteroposterior axis. This radial polarization also regulates esophageal elongation. Subsequently, cartilage development helps expand the tube diameter, which drives epithelial-cell reshaping to determine the optimal lumen shape for efficient respiration. These findings suggest a strategy in which straight-organ tubulogenesis is driven by subepithelial cell polarization and ring cartilage development.

Highlights d Human stem cell-derived lineages combine to generate multilayer gastric organoids d 3-germ-layer gastric organoids form glands and functionally innervated smooth muscle d Neural crest cells promote growth, patterning, and morphogenesis of gastric tissues d 3-germ-layer tissue engineering also generates complex fundic and esophageal organoids