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Developmental Dynamics : An Official... Mar 2004The primitive streak is the organizing center for amniote gastrulation. It defines the future embryonic midline and serves as a conduit of cell migration for germ layer... (Review)
Review
The primitive streak is the organizing center for amniote gastrulation. It defines the future embryonic midline and serves as a conduit of cell migration for germ layer formation. The migration patterns of endodermal and mesodermal precursors through the streak have been studied in great detail. Additional new breakthroughs recently have revealed the cell biological and molecular mechanisms that govern streak induction and patterning. These findings include (1) identification of the ontogeny and inductive signals of streak precursors, (2) the potential cellular mechanism of streak extension, and (3) the molecular and functional diversification along the anterior-posterior and mediolateral axes within the primitive streak. These findings indicate that amniote embryos initiate gastrulation by using both evolutionarily conserved and divergent mechanisms. The data also provide a foundation for understanding how the midline axis is defined and maintained during gastrulation of the amniotes.
Topics: Amniotic Fluid; Animals; Body Patterning; Cell Differentiation; Chick Embryo; Developmental Biology; Gastrula; Gene Expression Regulation, Developmental; Models, Biological; Signal Transduction; Time Factors
PubMed: 14991697
DOI: 10.1002/dvdy.10458 -
Anatomical Record (Hoboken, N.J. : 2007) Feb 2014In chick and mouse, heart fields undergo dynamic morphological spatiotemporal changes during heart tube formation. Here, the dynamic change in spatial polarity of such... (Review)
Review
In chick and mouse, heart fields undergo dynamic morphological spatiotemporal changes during heart tube formation. Here, the dynamic change in spatial polarity of such fields is discussed and a new perspective on the heart fields is proposed. The heart progenitor cells delaminate through the primitive streak and migrate in a semicircular trajectory craniolaterally forming the bilateral heart fields as part of the splanchnic mesoderm. They switch their polarity from anteroposterior to mediolateral. The anterior intestinal portal posterior descent inverts the newly formed heart field mediolateral polarity into lateromedial by 125° bending. The heart fields revert back to their original anteroposterior polarity and fuse at the midline forming a semi heart tube by completing their half circle movement. Several names and roles were assigned to different portions of the heart fields: posterior versus anterior, first versus second, and primary versus secondary heart field. The posterior and anterior heart fields define basically physical fields that form the inflow-outflow axis of the heart tube. The first and second heart fields are, in contrast, temporal fields of differentiating cardiomyocytes expressing myosin light chain 2a and undifferentiated and proliferating precardiac mesoderm expressing Isl1 gene, respectively. The two markers present a complementary pattern and are expressed transiently in all myocardial lineages. Thus, Isl1 is not restricted to a portion of the heart field or one of the two heart lineages as has been often assumed.
Topics: Animals; Body Patterning; Cell Lineage; Cell Polarity; Chickens; Heart; Hemodynamics; Mice; Models, Animal; Morphogenesis; Stem Cells
PubMed: 24443184
DOI: 10.1002/ar.22831 -
STAR Protocols Apr 2023Cardiac pericytes are a critical yet enigmatic cell type within the coronary microvasculature. Since primary human cardiac pericytes are not readily accessible, we...
Cardiac pericytes are a critical yet enigmatic cell type within the coronary microvasculature. Since primary human cardiac pericytes are not readily accessible, we present a protocol to generate them from human induced pluripotent stem cells (hiPSCs). Our protocol involves several steps, including the generation of intermediate cell types such as mid-primitive streak, lateral plate mesoderm, splanchnic mesoderm, septum transversum, and epicardium, before deriving cardiac pericytes. With hiPSC-derived cardiac pericytes, researchers can decipher the mechanisms underlying coronary microvascular dysfunction. For complete details on the use and execution of this protocol, please refer to Shen et al..
PubMed: 37119139
DOI: 10.1016/j.xpro.2023.102256 -
Nature Jun 2020Tissue sculpting during development has been attributed mainly to cellular events through processes such as convergent extension or apical constriction. However, recent...
Tissue sculpting during development has been attributed mainly to cellular events through processes such as convergent extension or apical constriction. However, recent work has revealed roles for basement membrane remodelling in global tissue morphogenesis. Upon implantation, the epiblast and extraembryonic ectoderm of the mouse embryo become enveloped by a basement membrane. Signalling between the basement membrane and these tissues is critical for cell polarization and the ensuing morphogenesis. However, the mechanical role of the basement membrane in post-implantation embryogenesis remains unknown. Here we demonstrate the importance of spatiotemporally regulated basement membrane remodelling during early embryonic development. Specifically, we show that Nodal signalling directs the generation and dynamic distribution of perforations in the basement membrane by regulating the expression of matrix metalloproteinases. This basement membrane remodelling facilitates embryo growth before gastrulation. The establishment of the anterior-posterior axis further regulates basement membrane remodelling by localizing Nodal signalling-and therefore the activity of matrix metalloproteinases and basement membrane perforations-to the posterior side of the embryo. Perforations on the posterior side are essential for primitive-streak extension during gastrulation by rendering the basement membrane of the prospective primitive streak more prone to breaching. Thus spatiotemporally regulated basement membrane remodelling contributes to the coordination of embryo growth, morphogenesis and gastrulation.
Topics: Animals; Basement Membrane; Blastocyst; Embryo, Mammalian; Embryonic Development; Extracellular Matrix; Female; Gastrula; Male; Matrix Metalloproteinases; Mice; Nodal Signaling Ligands; Primitive Streak
PubMed: 32523119
DOI: 10.1038/s41586-020-2264-2 -
Mechanisms of Development Sep 2020Gastrulation consists in the dramatic reorganisation of the epiblast, a one-cell thick epithelial sheet, into a multilayered embryo. In chick, the formation of the... (Review)
Review
Gastrulation consists in the dramatic reorganisation of the epiblast, a one-cell thick epithelial sheet, into a multilayered embryo. In chick, the formation of the internal layers requires the generation of a macroscopic convection-like flow, which involves up to 50,000 epithelial cells in the epiblast. These cell movements locate the mesendoderm precursors into the midline of the epiblast to form the primitive streak. There they acquire a mesenchymal phenotype, ingress into the embryo and migrate outward to populate the inner embryonic layers. This review covers what is currently understood about how cell behaviours ultimately cause these morphogenetic events and how they are regulated. We discuss 1) how the biochemical patterning of the embryo before gastrulation creates compartments of differential cell behaviours, 2) how the global epithelial flows arise from the coordinated actions of individual cells, 3) how the cells delaminate individually from the epiblast during the ingression, and 4) how cells move after the ingression following stereotypical migration routes. We conclude by exploring new technical advances that will facilitate future research in the chick model system.
Topics: Animals; Chick Embryo; Chickens; Gastrula; Gastrulation; Germ Layers; Mesoderm; Morphogenesis
PubMed: 32562871
DOI: 10.1016/j.mod.2020.103624 -
Development (Cambridge, England) Mar 2012When amniotes appeared during evolution, embryos freed themselves from intracellular nutrition; development slowed, the mid-blastula transition was lost and maternal... (Review)
Review
When amniotes appeared during evolution, embryos freed themselves from intracellular nutrition; development slowed, the mid-blastula transition was lost and maternal components became less important for polarity. Extra-embryonic tissues emerged to provide nutrition and other innovations. One such tissue, the hypoblast (visceral endoderm in mouse), acquired a role in fixing the body plan: it controls epiblast cell movements leading to primitive streak formation, generating bilateral symmetry. It also transiently induces expression of pre-neural markers in the epiblast, which also contributes to delay streak formation. After gastrulation, the hypoblast might protect prospective forebrain cells from caudalizing signals. These functions separate mesendodermal and neuroectodermal domains by protecting cells against being caught up in the movements of gastrulation.
Topics: Amnion; Animals; Biological Evolution; Body Patterning; Chick Embryo; Embryonic Induction; Endoderm; Gastrulation; Gene Expression Regulation, Developmental; Germ Layers; Mice; Nervous System; Nutritional Physiological Phenomena; Primitive Streak
PubMed: 22354839
DOI: 10.1242/dev.070730 -
Stem Cell Reports Oct 2022The mechanism governing the transition of human embryonic stem cells (hESCs) toward differentiated cells is only partially understood. To explore this transition, the...
The mechanism governing the transition of human embryonic stem cells (hESCs) toward differentiated cells is only partially understood. To explore this transition, the activity and expression of the ubiquitous phosphatidylinositol 3-kinase (PI3Kα and PI3Kβ) were modulated in primed hESCs. The study reports a pathway that dismantles the restraint imposed by the EZH2 polycomb repressor on an essential stemness gene, NODAL, and on transcription factors required to trigger primitive streak formation. The primitive streak is the site where gastrulation begins to give rise to the three embryonic cell layers from which all human tissues derive. The pathway involves a PI3Kβ non-catalytic action that controls nuclear/active RAC1 levels, activation of JNK (Jun N-terminal kinase) and nuclear β-catenin accumulation. β-Catenin deposition at promoters triggers release of the EZH2 repressor, permitting stemness maintenance (through control of NODAL) and correct differentiation by allowing primitive streak master gene expression. PI3Kβ epigenetic control of EZH2/β-catenin might be modulated to direct stem cell differentiation.
Topics: Cell Differentiation; Embryonic Stem Cells; Enhancer of Zeste Homolog 2 Protein; Gene Expression; Humans; JNK Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Primitive Streak; beta Catenin
PubMed: 36179694
DOI: 10.1016/j.stemcr.2022.09.003 -
The International Journal of... 2009Fate maps are required to address questions about the commitment and differentiation of precardiac cells. Here, we report a detailed study of the precardiac cells...
Fate maps are required to address questions about the commitment and differentiation of precardiac cells. Here, we report a detailed study of the precardiac cells located at the level of the primitive streak, employing different experiments with a variety of techniques combining double transplantations, microinjections and immunocytochemistry. Most cells of the more rostral segments of the primitive streak were found to contribute cells to the endodermal layer, adjacent to precardiac mesodermal cells of the heart forming region whose provenance was in the immediately more caudal segments of the primitive streak. We established a close spatio-temporal relationship between the two cell layers and the expression of their specific cardiac markers (cNkx-2.5, Bmp2, Cripto, Usmaar, dHand, GATA4, Pitx2, Hex, Fgf8, AMHC1 and VMHC1). We also analyzed the ability of precardiac cells to differentiate when they are transplanted to ectopic locations or are subjected to the influence of the organizer. We propose that the precardiac cells of the primitive streak form at least two groups with different significance. One, regulated by mediation of the organizer, is located preferentially in the more rostral region of the primitive streak. It consists of the prospective cells of the endoderm layer, with a hierarchic pattern of expression of different genes characterized by its capacity for induction and regulation of a second group of cells. This second group is located preferentially in the more caudal segments, and is fated to form the precardiac mesoderm, whose differentiation would be characterized by the expression of various specific genes.
Topics: Animals; Avian Proteins; Blastoderm; Cell Lineage; Cell Movement; Cell Transplantation; Chick Embryo; Chickens; Ectoderm; Embryo, Nonmammalian; Fluorescent Dyes; Gene Expression Regulation, Developmental; Homeodomain Proteins; Immunohistochemistry; In Situ Hybridization; Mesoderm; Myocardium; Primitive Streak; Quail; Time Factors; Transplantation, Heterologous
PubMed: 19247942
DOI: 10.1387/ijdb.072417cl -
Scientific Reports Nov 2016The primitive streak in peri-implantation embryos forms the mesoderm and endoderm and controls cell differentiation. The metabolic cues regulating primitive streak...
The primitive streak in peri-implantation embryos forms the mesoderm and endoderm and controls cell differentiation. The metabolic cues regulating primitive streak formation remain largely unknown. Here we utilised a mouse embryonic stem (ES) cell differentiation system and a library of well-characterised drugs to identify these metabolic factors. We found that statins, which inhibit the mevalonate metabolic pathway, suppressed primitive streak formation in vitro and in vivo. Using metabolomics and pharmacologic approaches we identified the downstream signalling pathway of mevalonate and revealed that primitive streak formation requires protein farnesylation but not cholesterol synthesis. A tagging-via-substrate approach revealed that nuclear lamin B1 and small G proteins were farnesylated in embryoid bodies and important for primitive streak gene expression. In conclusion, protein farnesylation driven by the mevalonate pathway is a metabolic cue essential for primitive streak formation.
Topics: Animals; Cell Differentiation; Down-Regulation; Embryoid Bodies; Gene Expression Regulation, Developmental; Metabolic Networks and Pathways; Metabolome; Metabolomics; Mevalonic Acid; Mice, Inbred ICR; Myocytes, Cardiac; Neurogenesis; Oligonucleotide Array Sequence Analysis; Organogenesis; Primitive Streak; Protein Prenylation; Zebrafish
PubMed: 27883036
DOI: 10.1038/srep37697 -
Cell Stem Cell Jun 2022In this issue of Cell Stem Cell, Simunovic et al. (2022) establish embryoids by combining embryonic and extraembryonic components derived from human pluripotent stem...
In this issue of Cell Stem Cell, Simunovic et al. (2022) establish embryoids by combining embryonic and extraembryonic components derived from human pluripotent stem cells. The embryoids resemble human embryos cultured to post-implantation stages in vitro with regard to morphology, symmetry breaking, and the formation of primitive streak-like cell types.
Topics: Embryo Implantation; Embryo, Mammalian; Humans; Pluripotent Stem Cells
PubMed: 35659870
DOI: 10.1016/j.stem.2022.05.009