Local cell interactions and self-amplifying individual cell ingression drive amniote gastrulation.
Gastrulation generates three layers of cells (ectoderm, mesoderm, endoderm) from a single sheet, while large scale cell movements occur across the entire embryo. In amniote (reptiles, birds, mammals) embryos, the deep layers arise by epithelial-to-mesenchymal transition (EMT) at a morphologically stable midline structure, the primitive streak (PS). We know very little about how these events are controlled or how the PS is maintained despite its continuously changing cellular composition. Using the chick, we show that isolated EMT events and ingression of individual cells start well before gastrulation. A Nodal-dependent 'community effect' then concentrates and amplifies EMT by positive feedback to form the PS as a zone of massive cell ingression. Computer simulations show that a combination of local cell interactions (EMT and cell intercalation) is sufficient to explain PS formation and the associated complex movements globally across a large epithelial sheet, without the need to invoke long-range signalling.DOI: http://dx.doi.org/10.7554/eLife.01817.001.
Department of Cell and Developmental Biology, University College London, London, United Kingdom ogv20@cam.ac.uk.
Octavian
O
Voiculescu
Division of Pediatric Surgery, Morgan Stanley Children's Hospital of New York-Presbyterian, New York, United States Department of Surgery, College of Physicians and Surgeons, Columbia University, New York, United States.
Lawrence
L
Bodenstein
Department of Cell and Developmental Biology, University College London, London, United Kingdom.
I-Jun
IJ
Lau
Department of Cell and Developmental Biology, University College London, London, United Kingdom c.stern@ucl.ac.uk.
Claudio D
CD
Stern
D000818:Animals; D002450:Cell Communication; D002642:Chick Embryo; D003198:Computer Simulation; D054262:Gastrulation; D008853:Microscopy
EMT; cell movements; computer simulation; epithelial–mesenchymal interactions; modelling; primitive streak