title: The Physical Basis of Coordinated Tissue Spreading in Zebrafish Gastrulation.
abstract: Embryo morphogenesis relies on highly coordinated movements of different tissues. However, remarkably little is known about how tissues coordinate their movements to shape the embryo. In zebrafish embryogenesis, coordinated tissue movements first become apparent during "doming," when the blastoderm begins to spread over the yolk sac, a process involving coordinated epithelial surface cell layer expansion and mesenchymal deep cell intercalations. Here, we find that active surface cell expansion represents the key process coordinating tissue movements during doming. By using a combination of theory and experiments, we show that epithelial surface cells not only trigger blastoderm expansion by reducing tissue surface tension, but also drive blastoderm thinning by inducing tissue contraction through radial deep cell intercalations. Thus, coordinated tissue expansion and thinning during doming relies on surface cells simultaneously controlling tissue surface tension and radial tissue contraction.
authors.affiliation: Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Morita
authors.affiliation: The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
authors.forename: Silvia
authors.initials: S
authors.lastname: Grigolon
authors.affiliation: Max-Planck-Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bock
authors.affiliation: Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
authors.forename: S F Gabriel
authors.initials: SF
authors.lastname: Krens
authors.affiliation: The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Max-Planck-Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany. Electronic address: guillaume.salbreux@crick.ac.uk.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Salbreux
authors.affiliation: Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria. Electronic address: heisenberg@ist.ac.at.
authors.forename: Carl-Philipp
authors.initials: CP
authors.lastname: Heisenberg
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D001756:Blastoderm / Q000166:cytology / Q000378:metabolism; D002450:Cell Communication; D002452:Cell Count; D002465:Cell Movement; D049109:Cell Proliferation; D003198:Computer Simulation; D004625:Embryo, Nonmammalian / Q000166:cytology; D054262:Gastrulation; D009024:Morphogenesis; D013312:Stress, Physiological; D013500:Surface Tension; D015027:Zebrafish / Q000196:embryology* / Q000502:physiology*
keywords: active fluid description of tissue spreading; gastrulation; interfacial tension; radial cell intercalation; surface cell expansion; zebrafish