Ectoderm: The outer of the three germ layers of an embryo.Embryonic Induction: The complex processes of initiating CELL DIFFERENTIATION in the embryo. The precise regulation by cell interactions leads to diversity of cell types and specific pattern of organization (EMBRYOGENESIS).Gastrula: The developmental stage that follows BLASTULA or BLASTOCYST. It is characterized by the morphogenetic cell movements including invagination, ingression, and involution. Gastrulation begins with the formation of the PRIMITIVE STREAK, and ends with the formation of three GERM LAYERS, the body plan of the mature organism.Mesoderm: The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.Gene Expression Regulation, Developmental: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.Body Patterning: The processes occurring in early development that direct morphogenesis. They specify the body plan ensuring that cells will proceed to differentiate, grow, and diversify in size and shape at the correct relative positions. Included are axial patterning, segmentation, compartment specification, limb position, organ boundary patterning, blood vessel patterning, etc.Nervous System: The entire nerve apparatus, composed of a central part, the brain and spinal cord, and a peripheral part, the cranial and spinal nerves, autonomic ganglia, and plexuses. (Stedman, 26th ed)Endoderm: The inner of the three germ layers of an embryo.Xenopus Proteins: Proteins obtained from various species of Xenopus. Included here are proteins from the African clawed frog (XENOPUS LAEVIS). Many of these proteins have been the subject of scientific investigations in the area of MORPHOGENESIS and development.Morphogenesis: The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.In Situ Hybridization: A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes.Chick Embryo: The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.Bone Morphogenetic Proteins: Bone-growth regulatory factors that are members of the transforming growth factor-beta superfamily of proteins. They are synthesized as large precursor molecules which are cleaved by proteolytic enzymes. The active form can consist of a dimer of two identical proteins or a heterodimer of two related bone morphogenetic proteins.Sea Urchins: Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.Neural Crest: The two longitudinal ridges along the PRIMITIVE STREAK appearing near the end of GASTRULATION during development of nervous system (NEURULATION). The ridges are formed by folding of NEURAL PLATE. Between the ridges is a neural groove which deepens as the fold become elevated. When the folds meet at midline, the groove becomes a closed tube, the NEURAL TUBE.Bone Morphogenetic Protein 4: A bone morphogenetic protein that is a potent inducer of bone formation. It also functions as a regulator of MESODERM formation during EMBRYONIC DEVELOPMENT.Homeodomain Proteins: Proteins encoded by homeobox genes (GENES, HOMEOBOX) that exhibit structural similarity to certain prokaryotic and eukaryotic DNA-binding proteins. Homeodomain proteins are involved in the control of gene expression during morphogenesis and development (GENE EXPRESSION REGULATION, DEVELOPMENTAL).Germ Layers: The three primary germinal layers (ECTODERM; ENDODERM; and MESODERM) developed during GASTRULATION that provide tissues and body plan of a mature organism. They derive from two early layers, hypoblast and epiblast.Xenopus: An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.Neural Plate: The region in the dorsal ECTODERM of a chordate embryo that gives rise to the future CENTRAL NERVOUS SYSTEM. Tissue in the neural plate is called the neuroectoderm, often used as a synonym of neural plate.Blastula: An early non-mammalian embryo that follows the MORULA stage. A blastula resembles a hollow ball with the layer of cells surrounding a fluid-filled cavity (blastocele). The layer of cells is called BLASTODERM.Xenopus laevis: The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.Embryonic Structures: The anatomical parts that make up an organism in the early stages of development.Extremities: The farthest or outermost projections of the body, such as the HAND and FOOT.Fibroblast Growth Factor 8: A fibroblast growth factor that preferentially activates FIBROBLAST GROWTH FACTOR RECEPTOR 4. It was initially identified as an androgen-induced growth factor and plays a role in regulating growth of human BREAST NEOPLASMS and PROSTATIC NEOPLASMS.Fibroblast Growth Factors: A family of small polypeptide growth factors that share several common features including a strong affinity for HEPARIN, and a central barrel-shaped core region of 140 amino acids that is highly homologous between family members. Although originally studied as proteins that stimulate the growth of fibroblasts this distinction is no longer a requirement for membership in the fibroblast growth factor family.Gastrulation: A process of complicated morphogenetic cell movements that reorganizes a bilayer embryo into one with three GERM LAYERS and specific orientation (dorsal/ventral; anterior/posterior). Gastrulation describes the germ layer development of a non-mammalian BLASTULA or that of a mammalian BLASTOCYST.Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.Limb Buds: Distinct regions of mesenchymal outgrowth at both flanks of an embryo during the SOMITE period. Limb buds, covered by ECTODERM, give rise to forelimb, hindlimb, and eventual functional limb structures. Limb bud cultures are used to study CELL DIFFERENTIATION; ORGANOGENESIS; and MORPHOGENESIS.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.Tissue Transplantation: Transference of tissue within an individual, between individuals of the same species, or between individuals of different species.Quail: Common name for two distinct groups of BIRDS in the order GALLIFORMES: the New World or American quails of the family Odontophoridae and the Old World quails in the genus COTURNIX, family Phasianidae.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Notochord: A cartilaginous rod of mesodermal cells at the dorsal midline of all CHORDATE embryos. In lower vertebrates, notochord is the backbone of support. In the higher vertebrates, notochord is a transient structure, and segments of the vertebral column will develop around it. Notochord is also a source of midline signals that pattern surrounding tissues including the NEURAL TUBE development.Wnt Proteins: Wnt proteins are a large family of secreted glycoproteins that play essential roles in EMBRYONIC AND FETAL DEVELOPMENT, and tissue maintenance. They bind to FRIZZLED RECEPTORS and act as PARACRINE PROTEIN FACTORS to initiate a variety of SIGNAL TRANSDUCTION PATHWAYS. The canonical Wnt signaling pathway stabilizes the transcriptional coactivator BETA CATENIN.Lens, Crystalline: A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.Paired Box Transcription Factors: A family of transcription factors that control EMBRYONIC DEVELOPMENT within a variety of cell lineages. They are characterized by a highly conserved paired DNA-binding domain that was first identified in DROSOPHILA segmentation genes.Otx Transcription Factors: A family of VERTEBRATE homeodomain proteins that share homology with orthodenticle protein, Drosophila. They regulate GENETIC TRANSCRIPTION and play an important role in EMBRYONIC DEVELOPMENT of the BRAIN.Genes, Homeobox: Genes that encode highly conserved TRANSCRIPTION FACTORS that control positional identity of cells (BODY PATTERNING) and MORPHOGENESIS throughout development. Their sequences contain a 180 nucleotide sequence designated the homeobox, so called because mutations of these genes often results in homeotic transformations, in which one body structure replaces another. The proteins encoded by homeobox genes are called HOMEODOMAIN PROTEINS.Zebrafish Proteins: Proteins obtained from the ZEBRAFISH. Many of the proteins in this species have been the subject of studies involving basic embryological development (EMBRYOLOGY).Nodal Protein: The founding member of the nodal signaling ligand family of proteins. Nodal protein was originally discovered in the region of the mouse embryo primitive streak referred to as HENSEN'S NODE. It is expressed asymmetrically on the left side in chordates and plays a critical role in the genesis of left-right asymmetry during vertebrate development.Branchial Region: A region, of SOMITE development period, that contains a number of paired arches, each with a mesodermal core lined by ectoderm and endoderm on the two sides. In lower aquatic vertebrates, branchial arches develop into GILLS. In higher vertebrates, the arches forms outpouchings and develop into structures of the head and neck. Separating the arches are the branchial clefts or grooves.Embryonic and Fetal Development: Morphological and physiological development of EMBRYOS or FETUSES.Chimera: An individual that contains cell populations derived from different zygotes.Hedgehog Proteins: A family of intercellular signaling proteins that play and important role in regulating the development of many TISSUES and organs. Their name derives from the observation of a hedgehog-like appearance in DROSOPHILA embryos with genetic mutations that block their action.Embryonic Development: Morphological and physiological development of EMBRYOS.Head: The upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth, and sense organs.Cell Lineage: The developmental history of specific differentiated cell types as traced back to the original STEM CELLS in the embryo.Embryo, Mammalian: The entity of a developing mammal (MAMMALS), generally from the cleavage of a ZYGOTE to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the FETUS.Central Nervous System: The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges.Triturus: A genus of aquatic newts in the Salamandridae family. During breeding season many Triturus males have a dorsal crest which also serves as an accessory respiratory organ. One of the common Triturus species is Triturus cristatus (crested newt).Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Strongylocentrotus purpuratus: A species of SEA URCHINS in the family Strongylocentrotidae found on the Pacific coastline from Alaska to Mexico. This species serves as a major research model for molecular developmental biology and other fields.Bone Morphogenetic Protein Receptors: A family of CELL SURFACE RECEPTORS that bind BONE MORPHOGENETIC PROTEINS. They are PROTEIN-SERINE-THREONINE KINASES that mediate SIGNAL TRANSDUCTION PATHWAYS through SMAD PROTEINS.SOXB1 Transcription Factors: A subclass of SOX transcription factors that are expressed in neuronal tissue where they may play a role in the regulation of CELL DIFFERENTIATION. Members of this subclass are generally considered to be transcriptional activators.Trans-Activators: Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.Epidermis: The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).Organizers, Embryonic: Cells in certain regions of an embryo that self-regulate embryonic development. These organizers have been found in dorsal and ventral poles of GASTRULA embryos, including Spemann organizer in amphibians, and Hensen node in chicken and mouse. These organizer cells communicate with each other via a network of secreted signaling proteins, such as BONE MORPHOGENETIC PROTEINS and their antagonists (chordin and noggin).Somites: Paired, segmented masses of MESENCHYME located on either side of the developing spinal cord (neural tube). Somites derive from PARAXIAL MESODERM and continue to increase in number during ORGANOGENESIS. Somites give rise to SKELETON (sclerotome); MUSCLES (myotome); and DERMIS (dermatome).Drosophila Proteins: Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.Drosophila: A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.Fibroblast Growth Factor 4: A HEPARIN binding fibroblast growth factor that may play a role in LIMB BUDS development.HMGB Proteins: A family of sequence-related proteins similar to HMGB1 PROTEIN that contains specific HMG-BOX DOMAINS.DNA-Binding Proteins: Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.Zebrafish: An exotic species of the family CYPRINIDAE, originally from Asia, that has been introduced in North America. They are used in embryological studies and to study the effects of certain chemicals on development.Chordata, Nonvertebrate: A portion of the animal phylum Chordata comprised of the subphyla CEPHALOCHORDATA; UROCHORDATA, and HYPEROTRETI, but not including the Vertebrata (VERTEBRATES). It includes nonvertebrate animals having a NOTOCHORD during some developmental stage.Activins: Activins are produced in the pituitary, gonads, and other tissues. By acting locally, they stimulate pituitary FSH secretion and have diverse effects on cell differentiation and embryonic development. Activins are glycoproteins that are hetero- or homodimers of INHIBIN-BETA SUBUNITS.Blastocyst: A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.MSX1 Transcription Factor: A homeodomain protein that interacts with TATA-BOX BINDING PROTEIN. It represses GENETIC TRANSCRIPTION of target GENES and plays a critical role in ODONTOGENESIS.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Blastoderm: A layer of cells lining the fluid-filled cavity (blastocele) of a BLASTULA, usually developed from a fertilized insect, reptilian, or avian egg.Fetal Proteins: Proteins that are preferentially expressed or upregulated during FETAL DEVELOPMENT.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Repressor Proteins: Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.Rhombencephalon: The posterior of the three primitive cerebral vesicles of an embryonic brain. It consists of myelencephalon, metencephalon, and isthmus rhombencephali from which develop the major BRAIN STEM components, such as MEDULLA OBLONGATA from the myelencephalon, CEREBELLUM and PONS from the metencephalon, with the expanded cavity forming the FOURTH VENTRICLE.Neural Tube: A tube of ectodermal tissue in an embryo that will give rise to the CENTRAL NERVOUS SYSTEM, including the SPINAL CORD and the BRAIN. Lumen within the neural tube is called neural canal which gives rise to the central canal of the spinal cord and the ventricles of the brain. For malformation of the neural tube, see NEURAL TUBE DEFECTS.Limb Deformities, Congenital: Congenital structural deformities of the upper and lower extremities collectively or unspecified.Wnt1 Protein: A proto-oncogene protein and member of the Wnt family of proteins. It is expressed in the caudal MIDBRAIN and is essential for proper development of the entire mid-/hindbrain region.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Culture Techniques: Methods of maintaining or growing biological materials in controlled laboratory conditions. These include the cultures of CELLS; TISSUES; organs; or embryo in vitro. Both animal and plant tissues may be cultured by a variety of methods. Cultures may derive from normal or abnormal tissues, and consist of a single cell type or mixed cell types.T-Box Domain Proteins: Proteins containing a region of conserved sequence, about 200 amino acids long, which encodes a particular sequence specific DNA binding domain (the T-box domain). These proteins are transcription factors that control developmental pathways. The prototype of this family is the mouse Brachyury (or T) gene product.Nerve Tissue ProteinsEye: The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Nodal Signaling Ligands: Members of the transforming growth factor superfamily that play a role in pattern formation and differentiation during the pregastrulation and GASTRULATION stages of chordate development. Several nodal signaling ligands are specifically involved in the genesis of left-right asymmetry during development. The protein group is named after a critical region of the vertebrate embryo PRIMITIVE STREAK referred to as HENSEN'S NODE.Pleurodeles: A genus of aquatic newts belonging to the family Salamandridae and sometimes referred to as "spiny" tritons. There are two species P. waltlii and P. poireti. P. waltlii is commonly used in the laboratory. Since this genus adapts to aquarium living, it is easy to maintain in laboratories.Coturnix: A genus of BIRDS in the family Phasianidae, order GALLIFORMES, containing the common European and other Old World QUAIL.AxisWnt3 Protein: A Wnt protein subtype that plays a role in cell-cell signaling during EMBRYONIC DEVELOPMENT and the morphogenesis of the developing NEURAL TUBE. Defects in Wnt3 protein are associated with autosomal recessive tetra-AMELIA in humans.Hemicentrotus: A genus of SEA URCHINS in the family Strongylocentrotidae with a hemicyclic apical disk and short spines.Goosecoid Protein: Goosecoid protein is a homeodomain protein that was first identified in XENOPUS. It is found in the SPEMANN ORGANIZER of VERTEBRATES and plays an important role in neuronal CELL DIFFERENTIATION and ORGANOGENESIS.Bone Morphogenetic Protein 2: A potent osteoinductive protein that plays a critical role in the differentiation of osteoprogenitor cells into OSTEOBLASTS.LIM-Homeodomain Proteins: A subclass of LIM domain proteins that include an additional centrally-located homeodomain region that binds AT-rich sites on DNA. Many LIM-homeodomain proteins play a role as transcriptional regulators that direct cell fate.Feathers: Flat keratinous structures found on the skin surface of birds. Feathers are made partly of a hollow shaft fringed with barbs. They constitute the plumage.Bone Morphogenetic Protein 7: A bone morphogenetic protein that is widely expressed during EMBRYONIC DEVELOPMENT. It is both a potent osteogenic factor and a specific regulator of nephrogenesis.Prosencephalon: The anterior of the three primitive cerebral vesicles of the embryonic brain arising from the NEURAL TUBE. It subdivides to form DIENCEPHALON and TELENCEPHALON. (Stedmans Medical Dictionary, 27th ed)Genes, Insect: The functional hereditary units of INSECTS.Amphibians: VERTEBRATES belonging to the class amphibia such as frogs, toads, newts and salamanders that live in a semiaquatic environment.Receptors, Fibroblast Growth Factor: Specific molecular sites or structures on cell membranes that react with FIBROBLAST GROWTH FACTORS (both the basic and acidic forms), their analogs, or their antagonists to elicit or to inhibit the specific response of the cell to these factors. These receptors frequently possess tyrosine kinase activity.Skull: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Eye Proteins

The surface ectoderm is essential for nephric duct formation in intermediate mesoderm. (1/1870)

The nephric duct is the first epithelial tubule to differentiate from intermediate mesoderm that is essential for all further urogenital development. In this study we identify the domain of intermediate mesoderm that gives rise to the nephric duct and demonstrate that the surface ectoderm is required for its differentiation. Removal of the surface ectoderm resulted in decreased levels of Sim-1 and Pax-2 mRNA expression in mesenchymal nephric duct progenitors, and caused inhibition of nephric duct formation and subsequent kidney development. The surface ectoderm expresses BMP-4 and we show that it is required for the maintenance of high-level BMP-4 expression in lateral plate mesoderm. Addition of a BMP-4-coated bead to embryos lacking the surface ectoderm restored normal levels of Sim-1 and Pax-2 mRNA expression in nephric duct progenitors, nephric duct formation and the initiation of nephrogenesis. Thus, BMP-4 signaling can substitute for the surface ectoderm in supporting nephric duct morphogenesis. Collectively, these data suggest that inductive interactions between the surface ectoderm, lateral mesoderm and intermediate mesoderm are essential for nephric duct formation and the initiation of urogenital development.  (+info)

Regulation of neurotrophin-3 expression by epithelial-mesenchymal interactions: the role of Wnt factors. (2/1870)

Neurotrophins regulate survival, axonal growth, and target innervation of sensory and other neurons. Neurotrophin-3 (NT-3) is expressed specifically in cells adjacent to extending axons of dorsal root ganglia neurons, and its absence results in loss of most of these neurons before their axons reach their targets. However, axons are not required for NT-3 expression in limbs; instead, local signals from ectoderm induce NT-3 expression in adjacent mesenchyme. Wnt factors expressed in limb ectoderm induce NT-3 in the underlying mesenchyme. Thus, epithelial-mesenchymal interactions mediated by Wnt factors control NT-3 expression and may regulate axonal growth and guidance.  (+info)

Fish swimbladder: an excellent mesodermal inductor in primary embryonic induction. (3/1870)

Swimbladder of the crucian carp, Carassius auratus, was found to be better as a vegatalizing tissue than other tissues, such as guinea-pig bone marrow, when presumptive ectoderm of Triturus gastrulae was used as reacting tissue. Swimbladder usually induced assemblies of highly organized mesodermal tissues, such as notochord, somites and pronephric tubules, some of which were covered by mesodermal epithelium without any epidermal covering. A special character of the effect of swimbladder was the rather frequent induction of solid balls of undifferentiated cells, which were identified as mesodermal or mesodermal and probably endodermal. These findings show that swimbladder has a strong and fast spreading vegetalizing effect on the responding presumptive ectoderm.  (+info)

Embryological study of a T/t locus mutation (tw73) affecting trophectoderm development. (4/1870)

Mouse embryos homozygous for the recessive lethal mutation tw73 show specific defects in trophectoderm shortly after implantation. The trophectoderm and ectoplacental cone fail to form the usual close association with the uterine decidua, and proliferation is markedly reduced. The embryo proper ceases to develop beyond the two-layered stage and degenerates and dies within 5 days of implantation.  (+info)

Bmp4 is required for the generation of primordial germ cells in the mouse embryo. (5/1870)

In many organisms the allocation of primordial germ cells (PGCs) is determined by the inheritance of maternal factors deposited in the egg. However, in mammals, inductive cell interactions are required around gastrulation to establish the germ line. Here, we show that Bmp4 homozygous null embryos contain no PGCs. They also lack an allantois, an extraembryonic mesodermal tissue derived, like the PGCs, from precursors in the proximal epiblast. Heterozygotes have fewer PGCs than normal, due to a reduction in the size of the founding population and not to an effect on its subsequent expansion. Analysis of beta-galactosidase activity in Bmp4(lacZneo) embryos reveals that prior to gastrulation, Bmp4 is expressed in the extraembryonic ectoderm. Later, Bmp4 is expressed in the extraembryonic mesoderm, but not in PGCs. Chimera analysis indicates that it is the Bmp4 expression in the extraembryonic ectoderm that regulates the formation of allantois and primordial germ cell precursors, and the size of the founding population of PGCs. The initiation of the germ line in the mouse therefore depends on a secreted signal from the previously segregated, extraembryonic, trophectoderm lineage.  (+info)

BMP7 acts in murine lens placode development. (6/1870)

Targeted inactivation of the Bmp7 gene in mouse leads to eye defects with late onset and variable penetrance (A. T. Dudley et al., 1995, Genes Dev. 9, 2795-2807; G. Luo et al., 1995, Genes Dev. 9, 2808-2820). Here we report that the expressivity of the Bmp7 mutant phenotype markedly increases in a C3H/He genetic background and that the phenotype implicates Bmp7 in the early stages of lens development. Immunolocalization experiments show that BMP7 protein is present in the head ectoderm at the time of lens placode induction. Using an in vitro culture system, we demonstrate that addition of BMP7 antagonists during the period of lens placode induction inhibits lens formation, indicating a role for BMP7 in lens placode development. Next, to integrate Bmp7 into a developmental pathway controlling formation of the lens placode, we examined the expression of several early lens placode-specific markers in Bmp7 mutant embryos. In these embryos, Pax6 head ectoderm expression is lost just prior to the time when the lens placode should appear, while in Pax6-deficient (Sey/Sey) embryos, Bmp7 expression is maintained. These results could suggest a simple linear pathway in placode induction in which Bmp7 functions upstream of Pax6 and regulates lens placode induction. At odds with this interpretation, however, is the finding that expression of secreted Frizzled Related Protein-2 (sFRP-2), a component of the Wnt signaling pathway which is expressed in prospective lens placode, is absent in Sey/Sey embryos but initially present in Bmp7 mutants. This suggests a different model in which Bmp7 function is required to maintain Pax6 expression after induction, during a preplacodal stage of lens development. We conclude that Bmp7 is a critical component of the genetic mechanism(s) controlling lens placode formation.  (+info)

Gap junction signalling mediated through connexin-43 is required for chick limb development. (7/1870)

During chick limb development the gap junction protein Connexin-43 (Cx43) is expressed in discrete spatially restricted domains in the apical ectodermal ridge (AER) and mesenchyme of the zone of polarising activity. Antisense oligonucleotides (ODNs) were used to investigate the role of Connexin-43 (Cx43) in the development of the chick limb bud. We have used unmodified ODNs in Pluronic F-127 gel, which is liquid at low temperature but sets at room temperature and so remains situated at the point of application. As a mild surfactant, the gel increases antisense ODN penetration and supplies ODNs to the embryo continually for 12-18 h. We have shown a strong decrease in Cx43 protein expression after application of specific antisense oligonucleotides but the abundance of a closely related protein, Connexin-32 (Cx32), was not affected. Application of antisense Cx43 ODNs at stages 8-15 HH before limb outgrowth resulted in dramatic limb phenotypes. About 40% of treated embryos exhibited defects such as truncation of the limb bud, fragmentation into two or more domains, or complete splitting of the limb bud into two or three branches. Molecular analysis of antisense treated embryos failed to detect Shh or Bmp-2 in anterior structures and suggested that extra lobes seen in nicked and split limbs were not a result of establishment of new signalling centres as found after the application of FGF to the flank. However, examination of markers for the AER showed a number of abnormalities. In severely truncated specimens we were unable to detect the expression of either Fgf-4 or Fgf-8. In both nicked and split limbs the expression of these genes was discontinuous. Down-regulation of Cx43 after the antisense application could be comparable to AER removal and results in distal truncation of the limb bud. Taken together these data suggest the existence of a feedback loop between the FGFs and signalling mediated by Cx43.  (+info)

Chick Barx2b, a marker for myogenic cells also expressed in branchial arches and neural structures. (8/1870)

We have isolated a new chicken gene, cBarx2b, which is related to mBarx2 in sequence, although the expression patterns of the two genes are quite different from one another. The cBarx2b gene is expressed in craniofacial structures, regions of the neural tube, and muscle groups in the limb, neck and cloaca. Perturbation of anterior muscle pattern by application of Sonic Hedgehog protein results in a posteriorization of cBarx2b expression.  (+info)

  • Initially the entire ventral ectoderm expresses many genetic markers characteristic of the AER (en-1, fgf-8, msx-2, dlx-2, cd44, and cx-43). (
  • Subsequently, the expression domain of most of these genes is restricted to the thickened ectoderm of the disto-ventral limb margin prior to forming an AER. (
  • In lgl, the expression of these genes is initiated but not maintained and the disto-ventral marginal ectoderm does not thicken. (
  • Novel regulatory interactions revealed by studies of murine limb pattern in Wnt-7a and En-1 mutants. (
  • Evidence from amphioxus suggests that ancestral chordates then concentrated neurosecretory cells in the anteriormost non-neural ectoderm. (
  • The epidermis of the skin originates from the less dorsal ectoderm which surrounds the neuroectoderm at the early gastrula stage of embryonic development. (
  • In contrast, expression of dermomyotomal markers can be caused by a contact-dependent signal from surface ectoderm and a diffusible signal from dorsal neural tube. (
  • Thus, in X. laevis embryos, the ectoderm is patterned by the secretion of BMP antagonists from the dorsal blastopore lip, or Spemann's organizer: BMP signalling is active ventrally, and induces the formation of surface ectoderm, whereas dorsal BMP signalling is inhibited, and the cells adopt a neural fate ( Hemmati-Brivanlou and Melton, 1997 ). (
  • These signals are initially expressed throughout the surface ectoderm, suggesting that another signal might be involved in patterning the optic vesicle initially into a dorsal RPE and ventral NR domain. (
  • During optic vesicle stages WNT-family members are expressed in the dorsal ectoderm and in the presumptive RPE. (
  • We propose a new model, where the optic vesicle is initially patterned into a dorsal RPE domain by both BMP and WNT signals released from the overlying ectoderm, while ventrally BMPs and FGFs are involved in NR specification. (
  • In contrast, Wnt7a expression is initiated and maintained in the dorsal ectoderm. (
  • In order to define the transcriptome of small groups of cells from a single germ layer and to retain spatial information, dorsal and ventral ectoderm was subdivided along the anterior-posterior and medial-lateral axes by microdissections. (
  • This provides a genetic code to define positional information of any ectoderm sample along the anterior-posterior and dorsal-ventral axes directly from its transcriptome. (
  • En-1 blocks Wnt-7a expression, preventing expression of Lmx-1b there, and establishes the dorsal-ventral axis. (
  • Bone morphogenetic proteins (BMPs) and FGFs are expressed in the surface ectoderm and are involved in RPE and NR specification respectively. (
  • One such gene us the EDA gene, which is a part of a group of genes that provide instructions for making proteins such as ectodysplasin A. Ectodysplasin A is part of a group of proteins that are important in signaling for the interactions between the ectoderm and the mesoderm. (
  • For instance, while ciliated sensory neurons arise from preplacodal ectoderm (PPE), previous lineage tracing studies suggest that both Gonadotropin releasing hormone 3 (Gnrh3) and microvillous sensory neurons derive from cranial neural crest (CNC). (
  • Using a previously established mouse ES-cell-based system that recapitulates the development of the ectoderm lineage we have identified a transient population that is consistent with definitive ectoderm. (
  • Initially the entire ventral ectoderm expresses many genetic markers characteristic of the AER (en-1, fgf-8, msx-2, dlx-2, cd44, and cx-43). (
  • The word ectoderm comes from the Greek ektos meaning "outside", and derma, meaning "skin. (
  • Dynamic expression of chicken Sox2 and Sox3 genes in ectoderm induced to form neural tissue. (
  • Subsequently, the expression domain of most of these genes is restricted to the thickened ectoderm of the disto-ventral limb margin prior to forming an AER. (
  • In lgl, the expression of these genes is initiated but not maintained and the disto-ventral marginal ectoderm does not thicken. (
  • Which of the following is a derivative of the ectoderm of the trilaminar embryo? (
  • First author George Britton and his supervisor Aryeh Warmflash discuss their new Development paper in which they apply advanced in vitro culturing techniques to investigate embryonic ectoderm patterning. (
  • Epidermis (integumentary, skin contribution) development will be briefly mentioned due to its ectoderm origin. (
  • Ectoderm is one of the three primary germ layers in the very early embryo. (
  • The ectoderm forms many of the sensory organs (eye, ear, nose), and is also the source of Rathke's pouch , an invaginating diverticulum of the stomodeal roof which ultimately detaches from the stomodeum and becomes the adenohypophysis of the pituitary gland. (
  • When the ectoderm is absent during this time, axons progress into the limb more slowly and, although a few sensory axons occasionally diverge a short distance from the plexus, they do not form a discrete nerve that travels to the skin. (
  • These results demonstrate that the target ectoderm is necessary for normal sensory axon growth and guidance in the hindlimb. (
  • Honig, M , Camilli, SJ & Xue, QS 2004, ' Ectoderm removal prevents cutaneous nerve formation and perturbs sensory axon growth in the chick hindlimb ', Developmental Biology , vol. 266, no. 1, pp. 27-42. (
  • Ectopic Sox3 caused induction of neural tissue from a very early stage of cell specification in the ectoderm and this effect was maintained such that large domains of additional CNS were apparent, including almost complete duplications of the CNS. (
  • If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue. (
  • The neuroectoderm (neural ectoderm) will form the retina, retinal pigment epithelium, the pigmented and non-pigmented layers of the ciliary and iris epithelium, the dilator and sphincter muscles of the iris and the optic nerve fibres. (
Novel skeletogenic patterning roles for the olfactory pit | Development
Novel skeletogenic patterning roles for the olfactory pit | Development (
A balance of FGF, BMP and WNT signalling positions the future placode territory in the head | Development
A balance of FGF, BMP and WNT signalling positions the future placode territory in the head | Development (
The outermost germ layer in a vertebrate gastrula | bartleby
The outermost germ layer in a vertebrate gastrula | bartleby (
Glossary. Part 14
Glossary. Part 14 (
Project MUSE - Epigenetics
Project MUSE - Epigenetics (
Neural plate - Wikipedia
Neural plate - Wikipedia (
Prenatal development | physiology |
Prenatal development | physiology | (
Perspective on the classification of ectodermal dysplasia - Jorgenson - 2009 - American Journal of Medical Genetics Part A -...
Perspective on the classification of ectodermal dysplasia - Jorgenson - 2009 - American Journal of Medical Genetics Part A -... (
5 weeks pregnant: Symptoms, hormones, baby development, and more
5 weeks pregnant: Symptoms, hormones, baby development, and more (
Derm | Definition of -derm at
Derm | Definition of -derm at (
Stem Cells
Stem Cells (
A Family of mRNAs Expressed in the Dorsal Ectoderm of Sea Urchin Embryos | SpringerLink
A Family of mRNAs Expressed in the Dorsal Ectoderm of Sea Urchin Embryos | SpringerLink (
Epidermis News, Articles and Research
Epidermis News, Articles and Research (
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Divergence of ectodermal and mesodermal gene regulatory network linkages in early development of sea urchins | PNAS (
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Stem cell - Wikipedia (
Embryology - Wikipedia
Embryology - Wikipedia ( - Neuroscience - Development of the Neural Tube - Neuroscience - Development of the Neural Tube (
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Ectomorphic | Definition of Ectomorphic by Merriam-Webster (
Mesoderm | embryology |
Mesoderm | embryology | (
Pax6- and Six3-Mediated Induction of Lens Cell Fate in Mouse and Human ES Cells
Pax6- and Six3-Mediated Induction of Lens Cell Fate in Mouse and Human ES Cells (
Congenital Hand Deformities: Overview, Incidence, Embryology
Congenital Hand Deformities: Overview, Incidence, Embryology (
IJMS  | Free Full-Text | Long-Term Stability and Differentiation Potential of Cryopreserved cGMP-Compliant Human Induced...
IJMS | Free Full-Text | Long-Term Stability and Differentiation Potential of Cryopreserved cGMP-Compliant Human Induced... (
Chordata Germ Layers |
Chordata Germ Layers | (
Review Chapters | StemBook
Review Chapters | StemBook (
Search | The Embryo Project Encyclopedia
Search | The Embryo Project Encyclopedia (
HON Mother & Child Glossary, Implantation & Embryonic Development
HON Mother & Child Glossary, Implantation & Embryonic Development (
Volume 119, Issue 11
JCI - Volume 119, Issue 11 (
Developmental pathways inferred from modularity, morphological integration and fluctuating asymmetry patterns in the human face...
Developmental pathways inferred from modularity, morphological integration and fluctuating asymmetry patterns in the human face... (
'embryo mammalian' Protocols and Video...
'embryo mammalian' Protocols and Video... (
Geometric control of ciliated band regulatory states in the sea urchin embryo | Development
Geometric control of ciliated band regulatory states in the sea urchin embryo | Development (