title: Conserved and divergent expression patterns of markers of axial development in eutherian mammals.
abstract: BACKGROUND
  Mouse embryos are cup shaped, but most nonrodent eutherian embryos are disk shaped. Extraembryonic ectoderm (ExEc), which may have essential roles in anterior-posterior (A-P) axis formation in mouse embryos, does not develop in many eutherian embryos. To assess A-P axis formation in eutherians, comparative analyses were made on rabbit, porcine, and Suncus embryos.
  
  
  RESULTS
  All embryos examined expressed Nodal initially throughout epiblast and visceral endoderm; its expression became restricted to the posterior region before gastrulation. Anterior visceral endoderm (AVE) genes were expressed in Otx2-positive visceral endoderm, with Dkk1 expression being most anterior. The mouse pattern of AVE formation was conserved in rabbit embryos, but had diverged in porcine and Suncus embryos. No structure that was molecularly equivalent to Bmp-positive ExEc, existed in rabbit or pig embryos. In Suncus embryos, A-P axis was determined at prehatching stage, and these embryos attached to uterine wall at future posterior side.
  
  
  CONCLUSIONS
  Nodal, but not Bmp, functions in epiblast and visceral endoderm development may be conserved in eutherians. AVE functions may also be conserved, but the pattern of its formation has diverged among eutherians. Roles of BMP and NODAL gradients in AVE formation seem to have been established in a subset of rodents.
authors.affiliation: Laboratory for Vertebrate Body Plan, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Laboratory for Vertebrate Body Plan, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kajikawa
authors.affiliation: Laboratory for Vertebrate Body Plan, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.|Misaki Marine Biological Station, Graduate School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kurokawa
authors.affiliation: Animal Development and Differentiation Research Unit, Animal Research Division, National Institute of Agrobiological Sciences (NIAS), Tsukuba-shi, Ibaraki, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Tokunaga
authors.affiliation: Laboratory of Animal Reproduction, Department of Animal Science and Resources, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Onishi
authors.affiliation: Ultrastructural Research Team, Biosystem Dynamics Group, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies (CLST), Chuo-ku, Kobe, Japan.
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Yonemura
authors.affiliation: Laboratory for Animal Resources and Genetic Engineering, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Laboratory for Animal Resources and Genetic Engineering, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyonari
authors.affiliation: Laboratory for Vertebrate Body Plan, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.|Laboratory for Animal Resources and Genetic Engineering, Center for Developmental Biology (CDB), RIKEN Kobe, Chuo-ku, Kobe, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Aizawa
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics; D004475:Ectoderm / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology*; D004707:Endoderm / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D055457:Nodal Protein / Q000235:genetics; D011817:Rabbits; D013552:Swine
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D055457:Nodal Protein
keywords: Bmp; Dkk1; Nodal; Otx2; Suncus; anterior visceral endoderm; anterior-posterior axis; extraembryonic ectoderm; pig; rabbit