...Yara Fadaili; Hui-Chun Lu; Hyung Chul Lee; Amra Ryazapova; Claudio D. Stern ABSTRACT In chick embryos before primitive streak formation, the outermost extra-embryonic region, known as the area opaca (AO), was generally thought to act only by providing nutrients and mechanical support to the embryo...

... these. Using experimental manipulation of early chick embryos, including misexpression of an inducer (VG1 or ACTIVIN) and an inhibitor (BMP4), we test two alternative models for their ability to explain how the site of primitive streak formation is positioned relative to the rest of the embryo. In one model...

... and regenerative medicine. Axis elongation Gastrulation Neuromesodermal progenitors Primitive streak Tail bud Pluripotent stem cells Lineage specification in the early vertebrate embryo is initiated during gastrulation (see Glossary, Box 1 ), which involves the formation of the three germ...

... of chick embryos in the early stages of primitive streak formation. Junctional tension of mesendoderm precursors in the epiblast is higher in junctions oriented in the direction of intercalation than in junctions oriented perpendicular to the direction of intercalation and higher than in junctions of other...

...Iain Martyn; Eric D. Siggia; Ali H. Brivanlou ABSTRACT Although fate maps of early embryos exist for nearly all model organisms, a fate map of the gastrulating human embryo remains elusive. Here, we use human gastruloids to piece together a rudimentary fate map for the human primitive streak (PS...

..., it binds a gene cohort involved in primitive streak formation at gastrulation, including NODAL , BMP4 and WNT3 . Comparing TCF7L1-bound sites with those bound by the WNT signaling effector β-catenin indicates that TCF7L1 acts largely on the WNT signaling pathway. TCF7L1 overlaps less with the pluripotency...

..., such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes such as reptiles. Planar cell movements are prime candidates to arrange specific modes of gastrulation but there is no consensus view on their role in different...

... by their position. Cell fate is progressively restricted by localised signalling cues from areas including the primitive streak. However, it is unknown whether this restriction accompanies, at the individual cell level, a reduction in potency. Investigation of these early transition events in vitro is possible via...

...Cantas Alev; Yuping Wu; Yukiko Nakaya; Guojun Sheng Mesoderm is formed during gastrulation. This process takes place at the blastopore in lower vertebrates and in the primitive streak (streak) in amniotes. The evolutionary relationship between the blastopore and the streak is unresolved...

...-dimensional body plan during gastrulation. In Tcf7l1 -/- embryos, specification of mesoderm is delayed, effectively uncoupling it from the induction of the primitive streak. Tcf7l1 repressor activity is necessary for a rapid switch in the response of pluripotent cells to Wnt/β-catenin stimulation, from one...

... of the primitive streak. Formation of an ectopic primitive streak, or streak expansion, has previously been reported in mutants lacking antagonists that target Nodal signaling. Here, we demonstrate that loss-of-function of a major bone morphogenetic protein (BMP) effector, Smad5, results in formation of an ectopic...

...Cantas Alev; Yuping Wu; Takeya Kasukawa; Lars M. Jakt; Hiroki R. Ueda; Guojun Sheng In birds and mammals, all mesoderm cells are generated from the primitive streak. Nascent mesoderm cells contain unique dorsoventral (D/V) identities according to their relative ingression position along the streak...

... a stepwise separation among its three main lineages, first between SMC progenitors and BC/EC common progenitors, and then between BCs and ECs. * Author for correspondence (e-mail: [email protected] ) 9 12 2008 © 2009. 2009 Chicken Chick Ventral mesoderm Primitive streak Smooth...

...)-cell self-renewal, such that up to 80% of the hES cells developed into the primitive streak (PS)/mesoderm progenitors, reminiscent of early mammalian embryogenesis. The formation of the PS/mesoderm progenitors essentially depended on the cooperative action of β-catenin together with Activin/Nodal...

...Noemí Cambray; Valerie Wilson In mammals, the primitive streak region and its descendant, the tail bud,are the source of nascent mesoderm and spinal cord throughout axial elongation. A localised population of long-term axial progenitors has been identified in a region of the tail bud...

... in mesoderm development. Unlike Bmpr1a -null embryos, which fail to gastrulate, Bmpr-MORE embryos initiate gastrulation, but the recruitment of prospective paraxial mesoderm cells to the primitive streak is delayed. This delay causes a more proximal distribution of cells with paraxial mesoderm character...

...Kunimasa Ohta; Sei Kuriyama; Tatsuya Okafuji; Ryu Gejima; Shin-ichi Ohnuma; Hideaki Tanaka Three classes of signaling molecule, VG1, WNT and BMP, play crucial roles in axis formation in the chick embryo. Although VG1 and WNT signals have a pivotal function in inducing the primitive streak...

.... * Author for correspondence (e-mail: [email protected] ) 23 5 2005 © 2006. 2006 Allantois Anteroposterior axis Apoptosis Brachyury Primitive streak Patterning Proliferation Vasculogenesis Mouse Yolk sac Heart The evolutionarily conserved T-box family of transcription...

... placenta. During gastrulation, the allantois grows into the exocoelomic cavity as a mesodermal extension of the posterior primitive streak. On the basis of morphology, gene expression and/or function, three cell types have been identified in the allantois: an outer layer of mesothelial cells, whose distal...

.... 2002 Clonal analysis laacZ Self-renewing cells Stem cell Primitive streak Presomitic mesoderm Segmentation Mouse embryo Clock Patterning A central aspect of vertebrate embryo development is the segmentation and specification of its longitudinal axis ( Keynes and Stern, 1988...