title: Nodal signal is required for morphogenetic movements of epiblast layer in the pre-streak chick blastoderm.
abstract: During axis formation in amniotes, posterior and lateral epiblast cells in the area pellucida undergo a counter-rotating movement along the midline to form primitive streak (Polonaise movements). Using chick blastoderms, we investigated the signaling involved in this cellular movement in epithelial-epiblast. In cultured posterior blastoderm explants from stage X to XI embryos, either Lefty1 or Cerberus-S inhibited initial migration of the explants on chamber slides. In vivo analysis showed that inhibition of Nodal signaling by Lefty1 affected the movement of DiI-marked epiblast cells prior to the formation of primitive streak. In Lefty1-treated embryos without a primitive streak, Brachyury expression showed a patchy distribution. However, SU5402 did not affect the movement of DiI-marked epiblast cells. Multi-cellular rosette, which is thought to be involved in epithelial morphogenesis, was found predominantly in the posterior half of the epiblast, and Lefty1 inhibited the formation of rosettes. Three-dimensional reconstruction showed two types of rosette, one with a protruding cell, the other with a ventral hollow. Our results suggest that Nodal signaling may have a pivotal role in the morphogenetic movements of epithelial epiblast including Polonaise movements and formation of multi-cellular rosette.
authors.affiliation: Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan.
authors.forename: Nariaki
authors.initials: N
authors.lastname: Yanagawa
authors.forename: Masahide
authors.initials: M
authors.lastname: Sakabe
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Sakata
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamagishi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakajima
mesh_terms: D000818:Animals; D001756:Blastoderm / Q000166:cytology / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002642:Chick Embryo; D002645:Chickens; D004848:Epithelium / Q000196:embryology; D005326:Fetal Proteins / Q000378:metabolism; D055458:Left-Right Determination Factors / Q000378:metabolism; D009024:Morphogenesis / Q000187:drug effects / Q000502:physiology*; D055457:Nodal Protein / Q000378:metabolism*; D011758:Pyrroles / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D020825:T-Box Domain Proteins / Q000378:metabolism; D000098908:Brachyury Protein
chemical_list: D005326:Fetal Proteins; D055458:Left-Right Determination Factors; D055457:Nodal Protein; D011758:Pyrroles; D020825:T-Box Domain Proteins; D000098908:Brachyury Protein; C105686:SU 5402