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.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.Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.AxisGene 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 Implantation: Endometrial implantation of EMBRYO, MAMMALIAN at the BLASTOCYST stage.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Embryonic Development: Morphological and physiological development of EMBRYOS.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.Mesoderm: The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.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.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.Allantois: An extra-embryonic membranous sac derived from the YOLK SAC of REPTILES; BIRDS; and MAMMALS. It lies between two other extra-embryonic membranes, the AMNION and the CHORION. The allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo.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.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.Ectoderm: The outer of the three germ layers of an embryo.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.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.Embryonic and Fetal Development: Morphological and physiological development of EMBRYOS or FETUSES.Avian Proteins: Proteins obtained from species of BIRDS.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).Chorion: The outermost extra-embryonic membrane surrounding the developing embryo. In REPTILES and BIRDS, it adheres to the shell and allows exchange of gases between the egg and its environment. In MAMMALS, the chorion evolves into the fetal contribution of the PLACENTA.Chorioallantoic Membrane: A highly vascularized extra-embryonic membrane, formed by the fusion of the CHORION and the ALLANTOIS. It is mostly found in BIRDS and REPTILES. It serves as a model for studying tumor or cell biology, such as angiogenesis and TISSUE TRANSPLANTATION.Blastoderm: A layer of cells lining the fluid-filled cavity (blastocele) of a BLASTULA, usually developed from a fertilized insect, reptilian, or avian egg.Embryo Loss: Early pregnancy loss during the EMBRYO, MAMMALIAN stage of development. In the human, this period comprises the second through eighth week after fertilization.Hypothalamo-Hypophyseal System: A collection of NEURONS, tracts of NERVE FIBERS, endocrine tissue, and blood vessels in the HYPOTHALAMUS and the PITUITARY GLAND. This hypothalamo-hypophyseal portal circulation provides the mechanism for hypothalamic neuroendocrine (HYPOTHALAMIC HORMONES) regulation of pituitary function and the release of various PITUITARY HORMONES into the systemic circulation to maintain HOMEOSTASIS.Cartilage: A non-vascular form of connective tissue composed of CHONDROCYTES embedded in a matrix that includes CHONDROITIN SULFATE and various types of FIBRILLAR COLLAGEN. There are three major types: HYALINE CARTILAGE; FIBROCARTILAGE; and ELASTIC CARTILAGE.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).Cleavage Stage, Ovum: The earliest developmental stage of a fertilized ovum (ZYGOTE) during which there are several mitotic divisions within the ZONA PELLUCIDA. Each cleavage or segmentation yields two BLASTOMERES of about half size of the parent cell. This cleavage stage generally covers the period up to 16-cell MORULA.Coturnix: A genus of BIRDS in the family Phasianidae, order GALLIFORMES, containing the common European and other Old World QUAIL.Blastomeres: Undifferentiated cells resulting from cleavage of a fertilized egg (ZYGOTE). Inside the intact ZONA PELLUCIDA, each cleavage yields two blastomeres of about half size of the parent cell. Up to the 8-cell stage, all of the blastomeres are totipotent. The 16-cell MORULA contains outer cells and inner cells.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).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.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Fertilization in Vitro: An assisted reproductive technique that includes the direct handling and manipulation of oocytes and sperm to achieve fertilization in vitro.Pituitary-Adrenal System: The interactions between the anterior pituitary and adrenal glands, in which corticotropin (ACTH) stimulates the adrenal cortex and adrenal cortical hormones suppress the production of corticotropin by the anterior pituitary.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.Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.Time Factors: Elements of limited time intervals, contributing to particular results or situations.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)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.Endoderm: The inner of the three germ layers of an embryo.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.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.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.Lathyrism: A paralytic condition of the legs caused by ingestion of lathyrogens, especially BETA-AMINOPROPIONITRILE or beta-N-oxalyl amino-L-alanine, which are found in the seeds of plants of the genus LATHYRUS.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Zygote: The fertilized OVUM resulting from the fusion of a male and a female gamete.Extremities: The farthest or outermost projections of the body, such as the HAND and FOOT.Extraembryonic Membranes: The thin layers of tissue that surround the developing embryo. There are four extra-embryonic membranes commonly found in VERTEBRATES, such as REPTILES; BIRDS; and MAMMALS. They are the YOLK SAC, the ALLANTOIS, the AMNION, and the CHORION. These membranes provide protection and means to transport nutrients and wastes.Chimera: An individual that contains cell populations derived from different zygotes.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).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.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).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.Heart: The hollow, muscular organ that maintains the circulation of the blood.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.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.Embryo Disposition: Utilization or disposal of an embryo that is fertilized but not immediately transplanted and resulting course of action.WingMuscles: Contractile tissue that produces movement in animals.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Morula: An early embryo that is a compact mass of about 16 BLASTOMERES. It resembles a cluster of mulberries with two types of cells, outer cells and inner cells. Morula is the stage before BLASTULA in non-mammalian animals or a BLASTOCYST in mammals.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.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.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.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.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.Cell Movement: The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.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.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).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.Cryopreservation: Preservation of cells, tissues, organs, or embryos by freezing. In histological preparations, cryopreservation or cryofixation is used to maintain the existing form, structure, and chemical composition of all the constituent elements of the specimens.Tissue Transplantation: Transference of tissue within an individual, between individuals of the same species, or between individuals of different species.Yolk Sac: The first of four extra-embryonic membranes to form during EMBRYOGENESIS. In REPTILES and BIRDS, it arises from endoderm and mesoderm to incorporate the EGG YOLK into the DIGESTIVE TRACT for nourishing the embryo. In placental MAMMALS, its nutritional function is vestigial; however, it is the source of INTESTINAL MUCOSA; BLOOD CELLS; and GERM CELLS. It is sometimes called the vitelline sac, which should not be confused with the VITELLINE MEMBRANE of the egg.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.Electroporation: A technique in which electric pulses of intensity in kilovolts per centimeter and of microsecond-to-millisecond duration cause a temporary loss of the semipermeability of CELL MEMBRANES, thus leading to ion leakage, escape of metabolites, and increased uptake by cells of drugs, molecular probes, and DNA.Bursa of Fabricius: An epithelial outgrowth of the cloaca in birds similar to the thymus in mammals. It atrophies within 6 months after birth and remains as a fibrous remnant in adult birds. It is composed of lymphoid tissue and prior to involution, is the site of B-lymphocyte maturation.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.Central Nervous System: The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges.Dicarbethoxydihydrocollidine: 1,4-Dihydro-2,4,6-trimethyl-3,5-pyridinedicarboxylic acid diethyl ester.Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Avian Sarcoma Viruses: Group of alpharetroviruses (ALPHARETROVIRUS) producing sarcomata and other tumors in chickens and other fowl and also in pigeons, ducks, and RATS.Mesonephros: One of a pair of excretory organs (mesonephroi) which grows caudally to the first pair (PRONEPHROI) during development. Mesonephroi are the permanent kidneys in adult amphibians and fish. In higher vertebrates, proneprhoi and most of mesonephroi degenerate with the appearance of metanephroi. The remaining ducts become WOLFFIAN DUCTS.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.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.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.Collagen: A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Cell Division: The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Xenopus: An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.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.Animals, Genetically Modified: ANIMALS whose GENOME has been altered by GENETIC ENGINEERING, or their offspring.Embryo Research: Experimentation on, or using the organs or tissues from, a human or other mammalian conceptus during the prenatal stage of development that is characterized by rapid morphological changes and the differentiation of basic structures. In humans, this includes the period from the time of fertilization to the end of the eighth week after fertilization.5-Aminolevulinate Synthetase: An enzyme of the transferase class that catalyzes condensation of the succinyl group from succinyl coenzyme A with glycine to form delta-aminolevulinate. It is a pyridoxyal phosphate protein and the reaction occurs in mitochondria as the first step of the heme biosynthetic pathway. The enzyme is a key regulatory enzyme in heme biosynthesis. In liver feedback is inhibited by heme. EC 2.3.1.37.Retina: The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.Single Embryo Transfer: The techniques used to select and/or place only one embryo from FERTILIZATION IN VITRO into the uterine cavity to establish a singleton pregnancy.Aminopropionitrile: Reagent used as an intermediate in the manufacture of beta-alanine and pantothenic acid.Allylisopropylacetamide: An allylic compound that acts as a suicide inactivator of CYTOCHROME P450 by covalently binding to its heme moiety or surrounding protein.Cloning, Organism: The formation of one or more genetically identical organisms derived by vegetative reproduction from a single cell. The source nuclear material can be embryo-derived, fetus-derived, or taken from an adult somatic cell.Organ Culture Techniques: A technique for maintenance or growth of animal organs in vitro. It refers to three-dimensional cultures of undisaggregated tissue retaining some or all of the histological features of the tissue in vivo. (Freshney, Culture of Animal Cells, 3d ed, p1)Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Fibroblasts: Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.Eye: 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.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.Egg Shell: A hard or leathery calciferous exterior covering of an egg.Trans-Activators: Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.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.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.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Ectogenesis: Embryonic and fetal development that takes place in an artificial environment in vitro.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.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.Motor Neurons: Neurons which activate MUSCLE CELLS.Nerve Tissue ProteinsNuclear Transfer Techniques: Methods of implanting a CELL NUCLEUS from a donor cell into an enucleated acceptor cell.Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.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.DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Hydrocortisone: The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Epithelium: One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.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.Pregnancy Rate: The ratio of the number of conceptions (CONCEPTION) including LIVE BIRTH; STILLBIRTH; and fetal losses, to the mean number of females of reproductive age in a population during a set time period.Cell Nucleus: Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Ovum: A mature haploid female germ cell extruded from the OVARY at OVULATION.Developmental Biology: The field of biology which deals with the process of the growth and differentiation of an organism.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Sea Urchins: Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.Seeds: The encapsulated embryos of flowering plants. They are used as is or for animal feed because of the high content of concentrated nutrients like starches, proteins, and fats. Rapeseed, cottonseed, and sunflower seed are also produced for the oils (fats) they yield.Neural Tube Defects: Congenital malformations of the central nervous system and adjacent structures related to defective neural tube closure during the first trimester of pregnancy generally occurring between days 18-29 of gestation. Ectodermal and mesodermal malformations (mainly involving the skull and vertebrae) may occur as a result of defects of neural tube closure. (From Joynt, Clinical Neurology, 1992, Ch55, pp31-41)Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Fibroblast Growth Factor 4: A HEPARIN binding fibroblast growth factor that may play a role in LIMB BUDS development.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Cell Lineage: The developmental history of specific differentiated cell types as traced back to the original STEM CELLS in the embryo.Tissue Culture Techniques: A technique for maintaining or growing TISSUE in vitro, usually by DIFFUSION, perifusion, or PERFUSION. The tissue is cultured directly after removal from the host without being dispersed for cell culture.Cell Count: The number of CELLS of a specific kind, usually measured per unit volume or area of sample.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.Kinetics: The rate dynamics in chemical or physical systems.Microscopy, Phase-Contrast: A form of interference microscopy in which variations of the refracting index in the object are converted into variations of intensity in the image. This is achieved by the action of a phase plate.Transcription, Genetic: The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.Embryology: The study of the development of an organism during the embryonic and fetal stages of life.Tissue Distribution: Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.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.Carbocyanines: Compounds that contain three methine groups. They are frequently used as cationic dyes used for differential staining of biological materials.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.Vitelline Membrane: The plasma membrane of the egg.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.Virus Cultivation: Process of growing viruses in live animals, plants, or cultured cells.Organogenesis: Formation of differentiated cells and complicated tissue organization to provide specialized functions.RNA: A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Sperm Injections, Intracytoplasmic: An assisted fertilization technique consisting of the microinjection of a single viable sperm into an extracted ovum. It is used principally to overcome low sperm count, low sperm motility, inability of sperm to penetrate the egg, or other conditions related to male infertility (INFERTILITY, MALE).6-Aminonicotinamide: A vitamin antagonist which has teratogenic effects.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Histocytochemistry: Study of intracellular distribution of chemicals, reaction sites, enzymes, etc., by means of staining reactions, radioactive isotope uptake, selective metal distribution in electron microscopy, or other methods.Tretinoin: An important regulator of GENE EXPRESSION during growth and development, and in NEOPLASMS. Tretinoin, also known as retinoic acid and derived from maternal VITAMIN A, is essential for normal GROWTH; and EMBRYONIC DEVELOPMENT. An excess of tretinoin can be teratogenic. It is used in the treatment of PSORIASIS; ACNE VULGARIS; and several other SKIN DISEASES. It has also been approved for use in promyelocytic leukemia (LEUKEMIA, PROMYELOCYTIC, ACUTE).Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Molecular Weight: The sum of the weight of all the atoms in a molecule.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Teratogens: An agent that causes the production of physical defects in the developing embryo.Epiphyses: The head of a long bone that is separated from the shaft by the epiphyseal plate until bone growth stops. At that time, the plate disappears and the head and shaft are united.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Truncus Arteriosus: The arterial trunk arising from the fetal heart. During development, it divides into AORTA and the PULMONARY ARTERY.Cell Polarity: Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.Primitive Streak: A linear band of rapidly proliferating cells that begins near the posterior end of an embryo and grows cranially. Primitive streak is formed during GASTRULATION by the convergent migration of primary ectodermal cells (EPIBLAST). The knot at the tip of the streak is called HENSEN NODE.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Neurulation: An early embryonic developmental process of CHORDATES that is characterized by morphogenic movements of ECTODERM resulting in the formation of the NEURAL PLATE; the NEURAL CREST; and the NEURAL TUBE. Improper closure of the NEURAL GROOVE results in congenital NEURAL TUBE DEFECTS.Fetal Viability: The potential of the FETUS to survive outside the UTERUS after birth, natural or induced. Fetal viability depends largely on the FETAL ORGAN MATURITY, and environmental conditions.Mesencephalon: The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the PONS and the DIENCEPHALON. Midbrain contains two major parts, the dorsal TECTUM MESENCEPHALI and the ventral TEGMENTUM MESENCEPHALI, housing components of auditory, visual, and other sensorimoter systems.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Stem Cells: Relatively undifferentiated cells that retain the ability to divide and proliferate throughout postnatal life to provide progenitor cells that can differentiate into specialized cells.Abnormalities, Drug-Induced: Congenital abnormalities caused by medicinal substances or drugs of abuse given to or taken by the mother, or to which she is inadvertently exposed during the manufacture of such substances. The concept excludes abnormalities resulting from exposure to non-medicinal chemicals in the environment.Mice, Inbred C57BLParthenogenesis: A unisexual reproduction without the fusion of a male and a female gamete (FERTILIZATION). In parthenogenesis, an individual is formed from an unfertilized OVUM that did not complete MEIOSIS. Parthenogenesis occurs in nature and can be artificially induced.Gestational Age: The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization.Curare: Plant extracts from several species, including genera STRYCHNOS and Chondodendron, which contain TETRAHYDROISOQUINOLINES that produce PARALYSIS of skeletal muscle. These extracts are toxic and must be used with the administration of artificial respiration.Egg Yolk: Cytoplasm stored in an egg that contains nutritional reserves for the developing embryo. It is rich in polysaccharides, lipids, and proteins.Rotation: Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)TritiumFertilization: The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.Oviducts: Ducts that serve exclusively for the passage of eggs from the ovaries to the exterior of the body. In non-mammals, they are termed oviducts. In mammals, they are highly specialized and known as FALLOPIAN TUBES.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.TailCorticosterone: An adrenocortical steroid that has modest but significant activities as a mineralocorticoid and a glucocorticoid. (From Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1437)Skull: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Gonads: The gamete-producing glands, OVARY or TESTIS.Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Oncogene Protein p55(v-myc): Transforming protein coded by myc oncogenes. The v-myc protein has been found in several replication-defective avian retrovirus isolates which induce a broad spectrum of malignancies.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.Cytoplasm: The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Simbu virus: A species in the ORTHOBUNYAVIRUS genus of the family BUNYAVIRIDAE family. Previously a large group of serotypes, most are now considered separate species.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.
  • Several genes show dorsoventrally restricted patterns of expression within the neural tube and the fate maps were used to investigate the relationship between one of these genes, Pax3, and progenitor cell dispersal and fate. (nih.gov)
  • These morphogenic changes are accompanied by the expression of chamber-specific genes exclusively in the ventral side and the outer curvature of the heart tube. (ahajournals.org)
  • One hypothesis to explain how differentiated cells have a specialized pool of proteins is that differentiating cells retain only the genes (DNA) that encode the proteins they need, and they lose all the other genes. (biologyreference.com)
  • Gurdon's classic experiment demonstrated that the nucleus of the differentiated cell still retains the full genome: no genes are lost as a cell's descendents specialize. (biologyreference.com)
  • Other experiments supported an alternative hypothesis: that cell specialization reflects the differential regulation of the full set of genes in each cell type. (biologyreference.com)
  • This means that all cells in a mature organism (muscle cells, brain cells) all have the same set of genes, but only a subset of those genes are turned 'on' in any specific cell type. (biologyreference.com)
  • More often than not, these signal molecules are released from other cells in the embryo and affect target cells by regulating the expression of certain genes in those cells. (biologyreference.com)
  • VegT , an activator of nodal and nodal -like genes, is expressed in the cells of the vegetal pole. (xenbase.org)
  • 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. (nih.gov)
  • In lgl, the expression of these genes is initiated but not maintained and the disto-ventral marginal ectoderm does not thicken. (nih.gov)
  • The chick embryo provides an excellent experimental system to test the function of the identified genes. (ucdenver.edu)
  • We are using the chick to functionally characterize the genes arising from the mutagenesis screen, as well as other developmentally important genes. (ucdenver.edu)
  • The evolutionary conservation of genes involved in patterning the primary body axes has revolutionized the fields of both developmental and evolutionary biology, and has spawned the field of EvoDevo. (pubmedcentralcanada.ca)
  • Two of the best studied examples of comparative molecular anatomy are the mutually exclusive expression of BMPs and their antagonists in the epidermal and neural ectoderm, respectively, and the conserved relative expression domains of neural identity genes that subsequently subdivide the nervous system along the dorsal-ventral (D/V) axis. (pubmedcentralcanada.ca)
  • The domains of expression of a number of different classes of genes share similar boundaries, indicating that there could be a basic subdivision of the ventral IR into four distinct regions. (jneurosci.org)
  • NICD associates with additional cofactors in the nucleus of the signal receiving cell to activate downstream target genes. (els.net)
  • c,d) Genetically marking progenitor cells using DNA recombinase expression to unblock expression of marker genes. (els.net)
  • Neither indian hedgehog nor desert hedgehog are expressed in these midline structures although mRNA of both genes was detected in other structures of the early chick embryo. (biomedcentral.com)
  • We have shown in mouse and chick, Notch activity is essential for both dynamic expression of all clock genes and for somite formation. (dundee.ac.uk)
  • Protein components are identified, their functions in developmental processes are known, and the time and place in the embryo of expression of the genes encoding them are known. (nap.edu)
  • dkk1 expression was normal in these embryos during the blastula period, indicating that zygotic functions of these genes are required for maintenance but not establishment of dkk1 expression. (deepdyve.com)
  • It turns other genes on or off, helping the progenitor cells inside the pockets to become tracheal cells. (elifesciences.org)
  • Looking at embryos with defects in other genes involved in pocket formation revealed why. (elifesciences.org)
  • How can a few embryonic cells, all of which have the exact same set of genes, organize a body and form very different structures such as eyes, hearts, limbs, and livers? (sunyorange.edu)
  • One of the important factors in this process is the set of signal molecules which inform cells of where they are in a developing body and give them instructions as to which genes they should activate. (sunyorange.edu)
  • Ectopic expression of Wnt genes can cause a duplication of the developing axis in frogs, resulting in double heads or even complete replicas of the longitudinal axis. (sunyorange.edu)
  • Our results demonstrate that anterior guidance decisions by CoPA axons are dependent on the function of planar cell polarity genes both prior to and after midline crossing. (biomedcentral.com)
  • The "canonical" Wnt/β-catenin pathway (a.k.a. cell-fate pathway) is mediated by the stabilization and transport of β-catenin into the nucleus, where it binds to transcription factors that regulate the expression of Wnt target genes, and thus specify cellular fates. (biomedcentral.com)
  • Some of the genes that PRH regulates encode proteins that are involved in control of the cell cycle or in growth factor signalling pathways. (biochemj.org)
  • One interesting group, the Hox cluster genes, determine the identity of cells along the longitudinal and limb axes of the body. (sunyorange.edu)
  • In the human body, human cheek cells not only possess all the genes they require to make cheek cell proteins, they also possess all the genes required to make the repertoire of proteins found in nerve cells. (sunyorange.edu)
  • Liver cells have all the genes that cells of the ovary require. (sunyorange.edu)
  • Bone cells have the same genes that are found in cardiac muscle cells. (sunyorange.edu)
  • Since mitotic division faithfully copies the chromosomes of the parent cells and equally divides them between two daughter cells, all nucleated cells in the body (with some minor exceptions in lymphocytes) possess the same genes for the same proteins. (sunyorange.edu)
  • Transcription factors in general determine which genes will be activated in each cell, thus inducing nerve cells to make a different set of proteins than are found in liver cells. (sunyorange.edu)
  • Group II includes clusters of Hox genes arranged in tandem which direct the development of the anterior-posterior axis in higher animals, which are referred to as Hox clusters. (sunyorange.edu)
  • Tissue-specific inactivation of hedgehog signaling in neural crest-derived mandibular mesenchyme led to expansion of BMP signaling activity to throughout the oral-aboral axis of the distal mandibular arch and subsequently duplication of dentary bone in the oral side of the mandible at the expense of tongue formation. (elifesciences.org)
  • To demonstrate this, Spemann and Mangold (1924) transplanted tissue from the dorsal blastoporal lip to the ventral region of a host embryo, which would not ordinarily become neurepithelium. (docme.ru)
  • The hallmarks of development are tissue growth and the generation of cell diversity, resulting in reproducibly patterned animals. (sciencemag.org)
  • Comparative molecular studies provide powerful tools for elucidating the origins of mechanisms for establishing the dorsal-ventral and anterior-posterior axes in bilaterians and reveal differences in the evolutionary pressures acting upon tissue patterning. (pubmedcentralcanada.ca)
  • Mesenchymal cells derived from the dermomyotome condense within connective tissue (mesenchymal) scaffolds to form 2 common muscle masses. (medscape.com)
  • Thus, trunk neural crest cells exit from a common location but are directed to distinct peripheral locations and respond to local microenvironmental signals to build functional tissue architectures along the vertebrate posterior axis. (biologists.org)
  • Cardiac tissue is derived essentially symmetrically from lateral mesodermal regions of the embryo that later fuse in the midline to form a tube ( 4 ). (sciencemag.org)
  • The yolk sac is an extraembryonic tissue that produces blood cells similar to the structure that surrounds the yolk in birds. (bionity.com)
  • Convergent extension results when cells intercalate to narrow the tissue and move it forward. (bionity.com)
  • b) Increasing tissue complexity by intercompartmental signalling to alter the identity of boundary cells and boundary cell signalling to alter the identity of cells within compartments. (els.net)
  • The progenitor cells of these three germ layers ingress into the embryonic organiser and the primitive streak where they form resident populations of stem cells for multiple tissue types. (dundee.ac.uk)
  • Nerve cells that survive the injury often must regrow axons, despite tissue changes such as cavity formation that obstruct growth. (spinalcordinjuryzone.com)
  • In experimental studies, which mostly involved techniques of cell and tissue transplantation and removal, the central role of cytoplasmic localizations and cell-lineage-restricted developmental fates was recognized in the development of certain invertebrates by the early 1900s. (nap.edu)
  • In vertebrate development, the importance of inductions (also called tissue interactions) was recognized in the 1920s, following the stunning organizer transplantation experiments by Spemann and Mangold (1924) on newt embryos. (nap.edu)
  • Our results show that the myocardium, from the time of its formation, is a polarized and regionalized tissue and point to the role of oriented clonal cell growth in cardiac chamber morphogenesis. (rupress.org)
  • J: mRNA for the 16-kDa proteolipid component of the H+ synthase is expressed in bilateral stripes of deep tissue ventral to the neural tube, demonstrating that signal along the length of the neural tube and in the head is not obligatory or artifactual at tail bud stages. (xenbase.org)
  • This suggests that notochordal cells might serve as tissue-specific progenitor cells within the disc and establishes the Noto-cre mouse as a unique tool to interrogate the contribution of notochordal cells to both intervertebral disc development and disc degeneration. (biomedsearch.com)
  • Because of the offsetting arrangement of condensed and loose portions of the lateral and ventral sclerotome tissue, the precartilaginous vertebral bodies are formed by tissue from 2 successive somite levels. (medscape.com)
  • Signaling inputs from multiple pathways are essential for the establishment of distinct cell and tissue types in the embryo. (sdbonline.org)
  • Embryonic retinal cells from embryonic day (E)7, E10, and E11 promoted the survival of ganglion cells, whereas cells from earlier or later stages of development or from other tissue sources did not. (arvojournals.org)
  • An immunohistochemical identification key for cell types in adult mouse prostatic and urethral tissue sections PLoS One. (usc.edu)
  • Motor neurons are the most ventral cell type generated followed, at progressively more dorsal positions, by distinct classes of interneurons. (nih.gov)
  • Development of vertebrate jaws involves patterning neural crest-derived mesenchyme cells into distinct subpopulations along the proximal-distal and oral-aboral axes. (elifesciences.org)
  • The roof plate on the dorsal side (via BMPs and Wnts) and the floor plate on the ventral side (via Shh) provide positional information that assigns cells to distinct progenitor domains [ 1 , 2 ]. (royalsocietypublishing.org)
  • The morphogen gradient is a fundamental concept in developmental biology, originally described by Lewis Wolpert's "French Flag" model for the developing chick limb bud, in which cells interpret different threshold concentrations of morphogen resulting in distinct fates ( Fig. 1A ) ( Tickle, Summerbell, & Wolpert, 1975 ). (pubmedcentralcanada.ca)
  • In imaginal discs, the progeny of these cells often create distinct patches or 'clones' of marked cells. (els.net)
  • A number of distinct neuronal populations are generated in r1, including cerebellar granule cells [ 2 ], the most populous neuron in the vertebrate CNS. (beds.ac.uk)
  • The CNC cells continue to proliferate and undergo epithelial-mesenchymal transition (EMT), and subsequently emigrate from the closing neural tube in several streams that target distinct areas. (nature.com)
  • She is currently applying single-cell methods to human brain to dissect the contributions of distinct cell types to Alzheimer's disease pathogenesis and investigate the mechanisms of tau-mediated neurodegeneration in human brain. (stanford.edu)
  • Cell culture studies suggest that P95 is a novel endocytic protein important to maintain the balance of distinct endosomal sub-populations and potentially regulates the sorting of signaling molecules between them (unpublished work, Zerial lab). (studylibde.com)
  • In embryos homozygous for a lethal allele of gsc , the anterior-most and middle pouches undergo a defective fusion event at stage 13, rather than remaining distinct. (sdbonline.org)
  • All these studies have suffered from one or more major shortcomings, the most significant of which has been the lack of a reliable cell marker to determine the contributions of graft cells to ectopic embryos. (docme.ru)
  • We here demonstrated that the knockdown of SPIG1 in the retinal ganglion cells (RGCs) of developing chick embryos induced the robust ectopic branching of dorsal RGC axons and failed to form a tight terminal zone at the proper position on the tectum. (jneurosci.org)
  • This finding was corroborated in Npn-2 null mice, in which we identified motor neuron cell bodies in ectopic positions in the PNS. (biomedcentral.com)
  • In situ lesions of the branch tips davies whereas inhibition of prostaglandin synthesis from arachidonic acid lipooxygenase inhibit prostaglandin synthetase cyclo oxygenase the constitutive isoenzyme that produces prostaglandins that stimulate the formation of ectopic tubules no abnormality was found exclusively in the tubule cells fail to develop specii c criteria for the study of the. (nationalnewstoday.com)
  • In addition to ectopic gene expression, a decrease in cell death in the anterior of the developing Dorking hindlimb was observed. (ufl.edu)
  • The other organizing center is the floor plate (FP), which is located ventrally and induces ventral progenitor domains by producing sonic hedgehog (Shh) ( Jessell, 2000 ). (biologists.org)
  • Fibroblast Growth Factor (FGF) signalling induces changes in cellular behaviour allowing cells in the embryo to move, to survive, to divide or to differentiate. (mdpi.com)
  • 1996 ) The chick limbless mutation causes abnormalities in limb bud dorsal-ventral patterning: implications for the mechanism of apical ridge formation. (biologists.org)
  • The upper extremity is first discretely visible as a bulge or limb bud that develops on the ventrolateral wall of the embryo on day 26 (4-mm crown-to-rump length) (see image below). (medscape.com)
  • The limb bud continues to grow outward from the ventral wall, and at day 32 it develops a somewhat flattened, paddle-shaped hand plate (8-mm crown-to-rump length). (medscape.com)
  • In both mouse and chick limb buds, the repressor form of Gli3 is present in an anterior-posterior gradient with the highest levels in the anterior part of the limb bud where Shh signaling is at its lowest levels. (biomedcentral.com)
  • The genetic data of the Shh, Gli3 and double-compound mutants indicate that the phenotype in the absence of Shh is caused by an excess in the Gli3R form that suppresses gene expression, cell survival and distal progression of limb bud development. (biomedcentral.com)
  • 1990 ) Segmentation in the chick embryo hindbrain is defined by cell lineage restriction. (biologists.org)
  • 1991 ) Formation and regeneration of rhombomere boundaries in the developing chick hindbrain. (biologists.org)
  • The most well‐defined molecular mechanism for compartmental cell segregation is the Eph-Ephrin signalling of the rhombomeres of the vertebrate hindbrain. (els.net)
  • Cerebellar granule cell precursors are specifically generated within the hindbrain segment, rhombomere 1, which is bounded rostrally by the midbrain/hindbrain isthmus and caudally by the boundary of the Hoxa2 expression domain. (beds.ac.uk)
  • We examined the response of granule cell precursors to the overexpression of Hoxa2 , which normally determines patterns of development specific to the hindbrain. (beds.ac.uk)
  • 1992 ) Expression patterns of engrailed-like proteins in the chick embryo. (biologists.org)
  • Each type of cell in a mature organism has a unique collection of proteins. (biologyreference.com)
  • The blueprints for making these proteins are found in the nucleus of each cell in the form of deoxyribonucleic acid (DNA). (biologyreference.com)
  • The AER and PZ work as a functional unit responsible for the outgrowth of the limb along the proximodistal axis, and the marginal blood vessel may convey messenger proteins that integrate this process. (medscape.com)
  • Furthermore, we found that truncated chick spalt proteins, similar to the truncated spalt protein expressed in the human congenital disorder Townes-Brocks syndrome, affect the nuclear localization of full-length spalt. (jove.com)
  • In addition PRH makes direct protein-protein interactions with many cellular proteins that influence the cell cycle. (biochemj.org)
  • A Wnt5 Activity Asymmetry and Intercellular Signaling via PCP Proteins Polarize Node Cells for Left-Right Symmetry BreakingDev Cell. (usc.edu)
  • Early on, Otx2 expression is diffuse throughout the optic vesicles but becomes restricted to their dorsal part when the vesicles contact the surface ectoderm. (sdbonline.org)
  • For example, when particular cells in a mammalian embryo activate the gene for the protein MyoD and thus begin making MyoD protein, they are determined to be muscle cells. (biologyreference.com)
  • The chick provides an experimentally amenable and rapid system to determine the function of a gene. (ucdenver.edu)
  • Furthermore, Mart-1 expressing C8161 cells acquire a gene signature of poorly aggressive C81-61 cells. (biologists.org)
  • Gene regulatory networks that specify different cell fates based on concentration may elicit different responses depending on regulatory mechanisms (eg, feedback) within the network ( Horinaka & Morishita, 2012 ). (pubmedcentralcanada.ca)
  • a) Heterozygous cells carry a marker gene on one of the two homologues. (els.net)
  • the gene situs inversus viscerum+ (or iv+ for short) was identified as playing a role in L-R axis formation. (cram.com)
  • To find out, Kondo and Hayashi imaged developing fly embryos and saw that the trachealess gene does not start pocket formation, but that it is essential to maintain the pockets. (elifesciences.org)
  • Regulating and reverting the adipo-osteogenic lineage decision of trabecular human bone marrow stromal cells (hBMSCs) represents a promising approach for osteoporosis therapy and prevention. (uni-wuerzburg.de)
  • The zona limitans intrathalamica (ZLI) is a lineage-restriction compartment and primary developmental boundary in the vertebrate forebrain (which is analogous to the human cerebrum) that serves as a signaling center and a restrictive border between the thalamus (also known as the dorsal thalamus) and the prethalamus (ventral thalamus). (wikipedia.org)
  • Many developmental boundaries have been studied: within the forebrain alone, the confirmed cell lineage restriction boundaries are the pallial-subpallial boundary (PSB) dividing the dorsal and ventral telencephalon, the diencephalon-midbrain boundary (DMB) posterior to the ZLI, and the ZLI. (wikipedia.org)
  • Despite discoveries of cell lineage restriction boundaries and compartments in the brain, many of the regions studied have been disproven as segmental boundaries. (wikipedia.org)
  • Isolated notochordal remnants may escape their lineage-specific destination in the nucleus pulposus and instead attach to the outer surfaces of the vertebral bodies , from which notochordal cells largely regress. (wikipedia.org)
  • In this study we have used a combination of live imaging, single cell lineage analyses, and perturbation of specific signaling pathways to dissect the specification of the adaxial cells of the zebrafish embryo. (prolekare.cz)
  • This concept faces many difficulties when applied to complex three dimensional tissues such as those that typify vertebrate development, where the direct lineage relationships of many cells remain ill defined and the complicated morphogenesis of many tissues precludes definition of models of equivalence. (prolekare.cz)
  • Recent studies suggest that several new types of cells derive from the CNC 4 , 5 , but the identification of all CNC derivatives remains a daunting task and requires new lineage-tracing tools. (nature.com)
  • There is limited information from lineage tracing studies in mice suggesting that cells that give rise to the distal regions of the respiratory tract (distal airway epithelium and alveoli) and proximal regions (trachea and proximal airways) have different origins. (stembook.org)
  • Our in vivo studies demonstrate that SynCAM interactions are required for axon-axon contacts in the dorsal root entry zone (DREZ) and proper pathfinding of sensory axons and their collaterals. (biologists.org)
  • Once the axons locate their targets, they must construct specialized structures to release neurotransmitters at synapses, while target cells must assemble and precisely locate the structures needed to respond to neurotransmitters. (spinalcordinjuryzone.com)
  • Also, distances in the adult CNS are much greater than in the embryo, and chemical signposts for navigating axons may have changed in the adult. (spinalcordinjuryzone.com)
  • Retinal ganglion cell (RGC) axons from different dorsal-ventral positions showed graded and biphasic response to Wnt3 in a concentration-dependent manner. (nih.gov)
  • Wnt3 repulsion is mediated by Ryk, expressed in a ventral-to-dorsal decreasing gradient, whereas attraction of dorsal axons at lower Wnt3 concentrations is mediated by Frizzled(s). (nih.gov)
  • Overexpression of Wnt3 in the lateral tectum repelled the termination zones of dorsal RGC axons in vivo. (nih.gov)
  • Sharply defined regions in developing tissues are not necessarily compartments: cells can also maintain regions using regionalised signalling to change their identities. (els.net)
  • An animal's nervous system is that network of specialized cells , tissues , and organs that coordinates the body's interaction with the environment, such as sensing the environment, monitoring organs, and coordinating the activity of muscles . (newworldencyclopedia.org)
  • Once the migrating CNC cells arrive at their destinations, they begin to differentiate into multiple types of cells that contribute to various tissues. (nature.com)
  • The abilities to differentiate into multiple cell types and contribute to many tissues make CNC an intriguing subject of research in developmental biology. (nature.com)
  • Bruce Lee Summary Summary Biological information processing in living systems like cells, tissues and organs critically depends on the physical interactions of molecular signaling components in time and space. (studylibde.com)
  • Shortly thereafter, the midgut protrudes dorsally, compressing the dorsal-most tissues of the embryo. (sdbonline.org)
  • During mouse early embryogenesis, PRH mRNA is first detected in extra-embryonic tissues [ 9 ] that are involved in anterioposterior axis formation and formation of the primitive vasculature and blood system [ 9 ]. (biochemj.org)
  • 6-9 ⇓ ⇓ ⇓ The failure of these growth factors to promote cardiomyogenic induction in more primitive precursor cells indicates that additional as of yet unidentified factors participate in the process. (ahajournals.org)
  • By gaining a better understanding of the function of the primitive streak and the main axes of development, they hope to contribute to the bigger picture of amniote embryology-that is, the early development of reptiles, birds , and mammals inside the amniotic fluid. (asu.edu)
  • While the authors admit that, as of yet, little is known about the mechanisms that initiate the formation of the primitive streak , there are a number of hypotheses pertaining to the directly-related formation of the axes in the embryo. (asu.edu)
  • Studies in whole chick embryo cultures have implicated the posterior marginal zone (PMZ) of the embryonic disc as a likely site of primitive streak induction . (asu.edu)
  • They suggested that these responsive cells are scattered randomly and aggregate into the initial primitive streak upon signaling from the PMZ. (asu.edu)
  • The avian equivalent of Spemann's organizer, Hensen's node, begins to lose its ability to induce a nervous system from area opaca epiblast cells at stage 4+, immediately after the full primitive streak stage. (sdbonline.org)
  • The first magnification of the embryo shows that the blastoderm cell layers have thickened to form the primitive streak and Hensen's node. (asu.edu)
  • At 8 days post-fertilization, the developing mouse embryo exhibits a depression-like structure on its ventral side, at the end of the primitive streak, termed the 'ventral node', as shown in figure 1 a . (royalsocietypublishing.org)
  • Hensen's node, located at the tip of the primitive streak, is considered as the homologue of the dorsal blastoporal lip, which contains the organizer. (pnas.org)
  • Cell marking studies using a variety of labeling procedures such as carbon particles ( 1 , 2 ), tritiated thymidine ( 3 ), quail-chicken transplantations ( 4 ), 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine (DiI) deposition or lysine-rhodamine-dextran (LRD) intracellular injection ( 5 , 6 ) have been carried out on chicken embryos cultured at the primitive streak stage for periods of time ranging from 24 to 48 hr. (pnas.org)
  • Intriguingly, this alternative sequence of domain induction is related to the asymmetrical morphogenesis of the primitive node and other axial organs in the chick. (biomedcentral.com)
  • Primitive streak formation is reputed as being 'the most important time in ones life' since it generates the three germ layers of the embryo proper. (dundee.ac.uk)
  • The cells below must be able to form the body of a primitive chordate (a lancelet). (sunyorange.edu)
  • C. From around E17-E18 the distal epithelial tubules differentiate into type I and type II cells and expand to form saccules (arrows), the primitive gas exchange region of the lung (E18, H&E, right panel). (stembook.org)
  • At the rostral end of the primitive streak, "the ectodermal cells are loosely arranged and are disposed in a ventrolateral direction to form the primitive node" although a surface swelling is not necessarily present (Heuser, Rock, and Hertig, 1945). (ehd.org)
  • The primitive node (fig. 7-10), first described as a Knoten by Hensen in 1876, has been recorded as present in practically all stage 7 embryos, and varies in length from 0.02 to 0.1 mm, In some instances (e.g. (ehd.org)
  • The animal cells are not determined because the micromeres can induce the animal cells to also take on mesodermal and endodermal fates. (wikipedia.org)
  • In the newly formed somite, an epithelial layer of mesodermal cells surrounds a central lumen termed the somitocoel which contains loose mesenchyme cells. (els.net)
  • In terms of developmental commitment, a cell can either be specified or it can be determined. (wikipedia.org)
  • Developmental compartments require that cells acquire stable regional identities and have mechanisms that prevent intermixing with unlike cells. (els.net)
  • Several alternative mechanisms have been proposed to segregate cells between specific developmental compartments. (els.net)
  • One of the central questions of developmental biology is how cells of equivalent potential-an equivalence group-come to adopt specific cellular fates. (prolekare.cz)
  • The mechanisms that are utilised to generate individual cell types from a set of equivalently fated set of precursors remains a central experimental focus of developmental biology. (prolekare.cz)
  • Among the highlights during the period of 1880-1940 were the detailed anatomical descriptions of developmental stages of embryos, including the first atlas of human embryos, reconstructed from microscopic sections, published by W. His, Sr., in 1880-1885. (nap.edu)
  • Perturbation of CNC cells during any developmental stages may result in defects known as neurocristopathies, which are among the most common birth defects in humans 6 . (nature.com)
  • In a 19-year career at Harvard, McMahon was the Frank B. Baird Jr., Professor of Science, chair of the Department of Cell and Developmental Biology, a founding faculty of the Department of Stem Cells and Regenerative Biology, and principal investigator of the Harvard Stem Cell Institute. (usc.edu)
  • the transcript of Xmsx-2B was observed in ventral and lateral sides of the embryo. (bioone.org)
  • The general body form and structural details of the embryo are well shown in both the dorsal and lateral views. (ehd.org)
  • We find that Wnt3 is expressed in a medial-lateral decreasing gradient in chick optic tectum and mouse superior colliculus. (nih.gov)
  • Therefore, a classical morphogen, Wnt3, acting as an axon guidance molecule, plays a role in retinotectal mapping along the medial-lateral axis, counterbalancing the medial-directed EphrinB1-EphB activity. (nih.gov)
  • It sprouts lateral to this that we are the egg regarding a wind in the world of these cells. (hooligani.ru)
  • They organize into ventral and lateral subdivisions. (medscape.com)
  • Cells in the lateral subdivision of a sclerotome also organize into condensed and loosely arranged groups, but their position is somewhat offset from similar areas in the ventral subdivision. (medscape.com)
  • there he studied the effects of heavy metals on mouse embryo development and was introduced to reading scientific articles. (sciencehistory.org)
  • The remaining epithelial cells differentiate into the dermomyotome. (els.net)
  • This ebook Success in Academic Surgery 2017 called been on all 24 institutions comparing from 5 to 30 cells( Table 2), from which six differentiate rendered in Figure 4, to loosen a prestigious distinction of small semen throughout the endothelial dermatome. (ohiodevelopment.com)
  • Transplants of micromeres lacking nuclear accumulation of β-catenin were unable to induce a second axis. (wikipedia.org)
  • This cytoplasm was segregated to future muscle cells and if transplanted could induce the formation of muscle cells. (wikipedia.org)
  • It was also shown that coinjection of Xmsx-2B with a dominant-negative BMP-4 receptor ( tBR ), which can induce formation of secondary axis when injected alone in ventral blastomeres, suppressed secondary axis formation. (bioone.org)
  • Previous studies not using cell markers have concluded that the craniocaudal level of the induced neuraxis is determined by the age of the donor, that is, young donors induce cranial neuraxial levels, whereas old donors induce caudal levels. (docme.ru)
  • Activating mutations of beta-catenin and HGF/Met induce cancer stem cells in head and neck and mammary gland tumors. (mdc-berlin.de)
  • Although rapid progress is being made in many areas of molecular cardiology, issues pertaining to the origins of heart-forming cells, the mechanisms responsible for cardiogenic induction, and the pathways that regulate cardiomyocyte proliferation during embryonic and adult life remain unanswered. (ahajournals.org)
  • Many of the major cell-signaling pathways studied in biology-Wnt, Fgf, Tgfb, etc.-work this way in some contexts. (pubmedcentralcanada.ca)
  • The various Wnt signaling pathways that act independently of β-catenin have been described as non-canonical and, despite their diverse functions, they can be broadly grouped into the so-called "Wnt cell polarity" pathway [ 11 ]. (biomedcentral.com)
  • For reference, an initial description of cardiomyogenic induction and morphogenesis is provided, which is followed by a summary of published cell cycle analyses during these stages of cardiac ontology. (ahajournals.org)
  • 13 These outer and inner curvatures play critical roles in the morphogenesis of the 4-chambered heart, as the individual chambers balloon out from the outer curvature due to the rapid proliferation of resident myocardial cells. (ahajournals.org)
  • In this study, therefore, we performed computer simulation of optic -cup morphogenesis considering cell proliferation and constriction. (nii.ac.jp)
  • The heart, which is the first organ to form in the embryo, provides a striking example of morphogenesis. (rupress.org)
  • Results reveal that co-culture of the highly aggressive and metastatic human melanoma cell line C8161 upregulate a marker of melanosome formation (Mart-1) in the presence of embryonic day 3.5 chick trunk dorsal root ganglia. (biologists.org)