title: Mitotic cell rounding and epithelial thinning regulate lumen growth and shape.
abstract: Many organ functions rely on epithelial cavities with particular shapes. Morphogenetic anomalies in these cavities lead to kidney, brain or inner ear diseases. Despite their relevance, the mechanisms regulating lumen dimensions are poorly understood. Here, we perform live imaging of zebrafish inner ear development and quantitatively analyse the dynamics of lumen growth in 3D. Using genetic, chemical and mechanical interferences, we identify two new morphogenetic mechanisms underlying anisotropic lumen growth. The first mechanism involves thinning of the epithelium as the cells change their shape and lose fluids in concert with expansion of the cavity, suggesting an intra-organ fluid redistribution process. In the second mechanism, revealed by laser microsurgery experiments, mitotic rounding cells apicobasally contract the epithelium and mechanically contribute to expansion of the lumen. Since these mechanisms are axis specific, they not only regulate lumen growth but also the shape of the cavity.
authors.affiliation: Department of Experimental &Health Sciences, Universitat Pompeu Fabra/PRBB, 08003 Barcelona, Spain.
authors.forename: Esteban
authors.initials: E
authors.lastname: Hoijman
authors.affiliation: Department of Experimental &Health Sciences, Universitat Pompeu Fabra/PRBB, 08003 Barcelona, Spain.
authors.forename: Davide
authors.initials: D
authors.lastname: Rubbini
authors.affiliation: Advanced Digital Microscopy, Institute for Research in Biomedicine, 08028 Barcelona, Spain.
authors.forename: Julien
authors.initials: J
authors.lastname: Colombelli
authors.affiliation: Department of Experimental &Health Sciences, Universitat Pompeu Fabra/PRBB, 08003 Barcelona, Spain.
authors.forename: Berta
authors.initials: B
authors.lastname: Alsina
mesh_terms: D000818:Animals; D048430:Cell Shape; D007758:Ear, Inner / Q000166:cytology / Q000196:embryology*; D004625:Embryo, Nonmammalian; D004847:Epithelial Cells / Q000166:cytology*; D021621:Imaging, Three-Dimensional; D007424:Intracellular Fluid / Q000378:metabolism; D008938:Mitosis; D038081:Organogenesis; D015027:Zebrafish