title: Planar cell movements and oriented cell division during early primitive streak formation in the mammalian embryo.
abstract: Formation of the mammalian primitive streak appears to rely on cell proliferation to a minor extent only, but compensating cell movements have not yet been directly observed. This study analyses individual cell migration and proliferation simultaneously, using multiphoton and differential interference contrast time-lapse microscopy of late pregastrulation rabbit blastocysts. Epiblast cells in the posterior gastrula extension area accumulated medially and displayed complex planar movements including U-turns and a novel type of processional cell movement. In the same area metaphase plates tended to be aligned parallel to the anterior-posterior axis, and statistical analysis showed that rotations of metaphase plates causing preferred orientation were near-complete 8 min before anaphase onset; in some cases, rotations were strikingly rapid, achieving up to 45° per min. The mammalian primitive streak appears to be formed initially with its typically minimal anteroposterior elongation by a combination of oriented cell divisions with dedicated planar cell movements.
authors.affiliation: Department of Anatomy and Embryology, Centre of Anatomy, University of Göttingen, Germany.
authors.forename: Viktoriya
authors.initials: V
authors.lastname: Halacheva
authors.forename: Mathias
authors.initials: M
authors.lastname: Fuchs
authors.forename: Jürgen
authors.initials: J
authors.lastname: Dönitz
authors.forename: Tobias
authors.initials: T
authors.lastname: Reupke
authors.forename: Bernd
authors.initials: B
authors.lastname: Püschel
authors.forename: Christoph
authors.initials: C
authors.lastname: Viebahn
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000502:physiology; D002455:Cell Division / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D016764:Cell Polarity; D049109:Cell Proliferation; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology* / Q000502:physiology*; D054262:Gastrulation; D006801:Humans; D036641:Microscopy, Fluorescence, Multiphoton; D008857:Microscopy, Interference; D054240:Primitive Streak / Q000166:cytology* / Q000502:physiology; D011817:Rabbits; D059008:Time-Lapse Imaging / Q000379:methods