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.Endoderm: The inner of the three germ layers of an embryo.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.Neoplasms, Germ Cell and Embryonal: Neoplasms composed of primordial GERM CELLS of embryonic GONADS or of elements of the germ layers of the EMBRYO, MAMMALIAN. The concept does not refer to neoplasms located in the gonads or present in an embryo or FETUS.Embryonic Stem Cells: Cells derived from the BLASTOCYST INNER CELL MASS which forms before implantation in the uterine wall. They retain the ability to divide, proliferate and provide progenitor cells that can differentiate into specialized cells.Mesoderm: The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.Ectoderm: The outer of the three germ layers of an embryo.Teratoma: A true neoplasm composed of a number of different types of tissue, none of which is native to the area in which it occurs. It is composed of tissues that are derived from three germinal layers, the endoderm, mesoderm, and ectoderm. They are classified histologically as mature (benign) or immature (malignant). (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1642)Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.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.Embryoid Bodies: Spontaneous aggregations of human embryonic stem cells that occur in vitro after culturing in a medium that lacks LEUKEMIC INHIBITORY FACTOR. The embryoid bodies can further differentiate into cells that represent different lineages.Pluripotent Stem Cells: Cells that can give rise to cells of the three different GERM LAYERS.Octamer Transcription Factor-3: An octamer transcription factor that is expressed primarily in totipotent embryonic STEM CELLS and GERM CELLS and is down-regulated during CELL DIFFERENTIATION.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.Wheat Germ Agglutinins: Lectins purified from the germinating seeds of common wheat (Triticum vulgare); these bind to certain carbohydrate moieties on cell surface glycoproteins and are used to identify certain cell populations and inhibit or promote some immunological or physiological activities. There are at least two isoforms of this lectin.Induced Pluripotent Stem Cells: Cells from adult organisms that have been reprogrammed into a pluripotential state similar to that of EMBRYONIC STEM CELLS.Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.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.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.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.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.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.Cell Lineage: The developmental history of specific differentiated cell types as traced back to the original STEM CELLS in the 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.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).Testis: The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.Cell Culture Techniques: Methods for maintaining or growing CELLS in vitro.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.Spermatogenesis: The process of germ cell development in the male from the primordial germ cells, through SPERMATOGONIA; SPERMATOCYTES; SPERMATIDS; to the mature haploid SPERMATOZOA.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.Tooth Germ: The collective tissues from which an entire tooth is formed, including the DENTAL SAC; ENAMEL ORGAN; and DENTAL PAPILLA. (From Jablonski, Dictionary of Dentistry, 1992)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.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.Feeder Cells: Cells used in COCULTURE TECHNIQUES which support the growth of the other cells in the culture. Feeder cells provide auxillary substances including attachment substrates, nutrients, or other factors that are needed for growth in culture.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.Nuclear Reprogramming: The process that reverts CELL NUCLEI of fully differentiated somatic cells to a pluripotent or totipotent state. This process can be achieved to a certain extent by NUCLEAR TRANSFER TECHNIQUES, such as fusing somatic cell nuclei with enucleated pluripotent embryonic stem cells or enucleated totipotent oocytes. GENE EXPRESSION PROFILING of the fused hybrid cells is used to determine the degree of reprogramming. Dramatic results of nuclear reprogramming include the generation of cloned mammals, such as Dolly the sheep in 1997.SOXF Transcription Factors: A subclass of closely-related SOX transcription factors. Members of this subclass are expressed in VASCULAR ENDOTHELIAL CELLS and may play a role in vasculogenesis.Embryonic Development: Morphological and physiological development of EMBRYOS.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).Testicular Neoplasms: Tumors or cancer of the TESTIS. Germ cell tumors (GERMINOMA) of the testis constitute 95% of all testicular neoplasms.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).Stage-Specific Embryonic Antigens: Cell-surface molecules that exhibit lineage-restricted patterns of expression during EMBRYONIC DEVELOPMENT. The antigens are useful markers in the identification of EMBRYONIC STEM CELLS.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).Blastoderm: A layer of cells lining the fluid-filled cavity (blastocele) of a BLASTULA, usually developed from a fertilized insect, reptilian, or avian egg.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.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.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.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.Karyotyping: Mapping of the KARYOTYPE of a cell.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.Karyotype: The full set of CHROMOSOMES presented as a systematized array of METAPHASE chromosomes from a photomicrograph of a single CELL NUCLEUS arranged in pairs in descending order of size and according to the position of the CENTROMERE. (From Stedman, 25th ed)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.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.Embryonic and Fetal Development: Morphological and physiological development of EMBRYOS or FETUSES.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.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)Germinoma: A malignant neoplasm of the germinal tissue of the GONADS; MEDIASTINUM; or pineal region. Germinomas are uniform in appearance, consisting of large, round cells with vesicular nuclei and clear or finely granular eosinophilic-staining cytoplasm. (Stedman, 265th ed; from DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, pp1642-3)Cell Dedifferentiation: A reverse developmental process in which terminally differentiated cells with specialized functions revert back to a less differentiated stage within their own CELL LINEAGE.Spermatogonia: Euploid male germ cells of an early stage of SPERMATOGENESIS, derived from prespermatogonia. With the onset of puberty, spermatogonia at the basement membrane of the seminiferous tubule proliferate by mitotic then meiotic divisions and give rise to the haploid SPERMATOCYTES.Sertoli Cells: Supporting cells projecting inward from the basement membrane of SEMINIFEROUS TUBULES. They surround and nourish the developing male germ cells and secrete ANDROGEN-BINDING PROTEIN and hormones such as ANTI-MULLERIAN HORMONE. The tight junctions of Sertoli cells with the SPERMATOGONIA and SPERMATOCYTES provide a BLOOD-TESTIS BARRIER.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.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.Seminiferous Tubules: The convoluted tubules in the TESTIS where sperm are produced (SPERMATOGENESIS) and conveyed to the RETE TESTIS. Spermatogenic tubules are composed of developing germ cells and the supporting SERTOLI CELLS.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.Cell Line: Established cell cultures that have the potential to propagate indefinitely.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.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.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.Kruppel-Like Transcription Factors: A family of zinc finger transcription factors that share homology with Kruppel protein, Drosophila. They contain a highly conserved seven amino acid spacer sequence in between their ZINC FINGER MOTIFS.Receptor, EphB1: An eph family receptor found primarily in the nervous system. In the embryonic BRAIN EphB1 receptor expression occurs in the mantle layer and increases with the progression of embryogenesis. In adult brain it is found in the several regions including the CEREBELLUM; CEREBRAL CORTEX; and CAUDATE NUCLEUS; and PUTAMEN.Gonads: The gamete-producing glands, OVARY or TESTIS.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.Spermatocytes: Male germ cells derived from SPERMATOGONIA. The euploid primary spermatocytes undergo MEIOSIS and give rise to the haploid secondary spermatocytes which in turn give rise to SPERMATIDS.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.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.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.Spermatids: Male germ cells derived from the haploid secondary SPERMATOCYTES. Without further division, spermatids undergo structural changes and give rise to SPERMATOZOA.Chimera: An individual that contains cell populations derived from different zygotes.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.Germ Cells: The reproductive cells in multicellular organisms at various stages during GAMETOGENESIS.Xenopus: An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.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.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.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.Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Hepatocyte Nuclear Factor 3-beta: A forkhead transcription factor that regulates expression of metabolic GENES and is involved in EMBRYONIC DEVELOPMENT. Mutations in HNF-3beta have been associated with CONGENITAL HYPERINSULINISM.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.Fibroblasts: Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.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.Zygote: The fertilized OVUM resulting from the fusion of a male and a female gamete.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.Urochordata: A subphylum of chordates intermediate between the invertebrates and the true vertebrates. It includes the Ascidians.GATA Transcription Factors: A family of transcription factors that contain two ZINC FINGER MOTIFS and bind to the DNA sequence (A/T)GATA(A/G).Seminoma: A radiosensitive, malignant neoplasm of the testis, thought to be derived from primordial germ cells of the sexually undifferentiated embryonic gonad. There are three variants: classical (typical), the most common type; anaplastic; and spermatocytic. The classical seminoma is composed of fairly well differentiated sheets or cords of uniform polygonal or round cells (seminoma cells), each cell having abundant clear cytoplasm, distinct cell membranes, a centrally placed round nucleus, and one or more nucleoli. In the female, a grossly and histologically identical neoplasm, known as dysgerminoma, occurs. (Dorland, 27th ed)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.Fibroblast Growth Factor 4: A HEPARIN binding fibroblast growth factor that may play a role in LIMB BUDS development.Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.Time Factors: Elements of limited time intervals, contributing to particular results or situations.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.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Fetal Proteins: Proteins that are preferentially expressed or upregulated during FETAL DEVELOPMENT.Multipotent Stem Cells: Specialized stem cells that are committed to give rise to cells that have a particular function; examples are MYOBLASTS; MYELOID PROGENITOR CELLS; and skin stem cells. (Stem Cells: A Primer [Internet]. Bethesda (MD): National Institutes of Health (US); 2000 May [cited 2002 Apr 5]. Available from: http://www.nih.gov/news/stemcell/primer.htm)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.Parthenogenesis: 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.Gene Expression Profiling: The determination of the pattern of genes expressed at the level of GENETIC TRANSCRIPTION, under specific circumstances or in a specific cell.Cell Transplantation: Transference of cells within an individual, between individuals of the same species, or between individuals of different species.Stem Cell Transplantation: The transfer of STEM CELLS from one individual to another within the same species (TRANSPLANTATION, HOMOLOGOUS) or between species (XENOTRANSPLANTATION), or transfer within the same individual (TRANSPLANTATION, AUTOLOGOUS). The source and location of the stem cells determines their potency or pluripotency to differentiate into various cell types.Mice, SCID: Mice homozygous for the mutant autosomal recessive gene "scid" which is located on the centromeric end of chromosome 16. These mice lack mature, functional lymphocytes and are thus highly susceptible to lethal opportunistic infections if not chronically treated with antibiotics. The lack of B- and T-cell immunity resembles severe combined immunodeficiency (SCID) syndrome in human infants. SCID mice are useful as animal models since they are receptive to implantation of a human immune system producing SCID-human (SCID-hu) hematochimeric mice.Cell Proliferation: All of the processes involved in increasing CELL NUMBER including CELL DIVISION.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).Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Embryonal Carcinoma Stem Cells: The malignant stem cells of TERATOCARCINOMAS, which resemble pluripotent stem cells of the BLASTOCYST INNER CELL MASS. The EC cells can be grown in vitro, and experimentally induced to differentiate. They are used as a model system for studying early embryonic cell differentiation.Transforming Growth Factor beta: A factor synthesized in a wide variety of tissues. It acts synergistically with TGF-alpha in inducing phenotypic transformation and can also act as a negative autocrine growth factor. TGF-beta has a potential role in embryonal development, cellular differentiation, hormone secretion, and immune function. TGF-beta is found mostly as homodimer forms of separate gene products TGF-beta1, TGF-beta2 or TGF-beta3. Heterodimers composed of TGF-beta1 and 2 (TGF-beta1.2) or of TGF-beta2 and 3 (TGF-beta2.3) have been isolated. The TGF-beta proteins are synthesized as precursor proteins.Meiosis: A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.Oogenesis: The process of germ cell development in the female from the primordial germ cells through OOGONIA to the mature haploid ova (OVUM).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.Cell Adhesion: Adherence of cells to surfaces or to other cells.Stem Cell Research: Experimentation on STEM CELLS and on the use of stem cells.Smear Layer: Adherent debris produced when cutting the enamel or dentin in cavity preparation. It is about 1 micron thick and its composition reflects the underlying dentin, although different quantities and qualities of smear layer can be produced by the various instrumentation techniques. Its function is presumed to be protective, as it lowers dentin permeability. However, it masks the underlying dentin and interferes with attempts to bond dental material to the dentin.Amniotic Fluid: A clear, yellowish liquid that envelopes the FETUS inside the sac of AMNION. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (AMNIOCENTESIS).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.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.Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.Mice, Inbred C57BLVertebrates: Animals having a vertebral column, members of the phylum Chordata, subphylum Craniata comprising mammals, birds, reptiles, amphibians, and fishes.Lentivirus: A genus of the family RETROVIRIDAE consisting of non-oncogenic retroviruses that produce multi-organ diseases characterized by long incubation periods and persistent infection. Lentiviruses are unique in that they contain open reading frames (ORFs) between the pol and env genes and in the 3' env region. Five serogroups are recognized, reflecting the mammalian hosts with which they are associated. HIV-1 is the type species.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Cell Shape: The quality of surface form or outline of CELLS.Ovary: The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.Embryo Culture Techniques: The technique of maintaining or growing mammalian EMBRYOS in vitro. This method offers an opportunity to observe EMBRYONIC DEVELOPMENT; METABOLISM; and susceptibility to TERATOGENS.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.Organogenesis: Formation of differentiated cells and complicated tissue organization to provide specialized functions.Triticum: A plant genus of the family POACEAE that is the source of EDIBLE GRAIN. A hybrid with rye (SECALE CEREALE) is called TRITICALE. The seed is ground into FLOUR and used to make BREAD, and is the source of WHEAT GERM AGGLUTININS.Adult Stem Cells: Cells with high proliferative and self renewal capacities derived from adults.High Mobility Group Proteins: A family of low-molecular weight, non-histone proteins found in chromatin.Cell Transdifferentiation: A naturally occurring phenomenon where terminally differentiated cells dedifferentiate to the point where they can switch CELL LINEAGES. The cells then differentiate into other cell types.Gametogenesis: The process of germ cell development from the primordial GERM CELLS to the mature haploid GAMETES: ova in the female (OOGENESIS) or sperm in the male (SPERMATOGENESIS).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.Digestive System: A group of organs stretching from the MOUTH to the ANUS, serving to breakdown foods, assimilate nutrients, and eliminate waste. In humans, the digestive system includes the GASTROINTESTINAL TRACT and the accessory glands (LIVER; BILIARY TRACT; PANCREAS).Genes, Lethal: Genes whose loss of function or gain of function MUTATION leads to the death of the carrier prior to maturity. They may be essential genes (GENES, ESSENTIAL) required for viability, or genes which cause a block of function of an essential gene at a time when the essential gene function is required for viability.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.Epigenesis, Genetic: A genetic process by which the adult organism is realized via mechanisms that lead to the restriction in the possible fates of cells, eventually leading to their differentiated state. Mechanisms involved cause heritable changes to cells without changes to DNA sequence such as DNA METHYLATION; HISTONE modification; DNA REPLICATION TIMING; NUCLEOSOME positioning; and heterochromatization which result in selective gene expression or repression.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Epithelium: One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.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.Seminiferous Epithelium: The epithelium lining the seminiferous tubules composed of primary male germ cells (SPERMATOGONIA) and supporting SERTOLI CELLS. As SPERMATOGENESIS proceeds, the developing germ cells migrate toward the lumen. The adluminal compartment, the inner two thirds of the tubules, contains SPERMATOCYTES and the more advanced germ cells.Receptors, Notch: A family of conserved cell surface receptors that contain EPIDERMAL GROWTH FACTOR repeats in their extracellular domain and ANKYRIN repeats in their cytoplasmic domains. The cytoplasmic domain of notch receptors is released upon ligand binding and translocates to the CELL NUCLEUS where it acts as transcription factor.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.Gene Knockdown Techniques: The artificial induction of GENE SILENCING by the use of RNA INTERFERENCE to reduce the expression of a specific gene. It includes the use of DOUBLE-STRANDED RNA, such as SMALL INTERFERING RNA and RNA containing HAIRPIN LOOP SEQUENCE, and ANTI-SENSE OLIGONUCLEOTIDES.Nuclear Proteins: Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.Organ Specificity: Characteristic restricted to a particular organ of the body, such as a cell type, metabolic response or expression of a particular protein or antigen.Sea Urchins: Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.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)Dysgerminoma: A malignant ovarian neoplasm, thought to be derived from primordial germ cells of the sexually undifferentiated embryonic gonad. It is the counterpart of the classical seminoma of the testis, to which it is both grossly and histologically identical. Dysgerminomas comprise 16% of all germ cell tumors but are rare before the age of 10, although nearly 50% occur before the age of 20. They are generally considered of low-grade malignancy but may spread if the tumor extends through its capsule and involves lymph nodes or blood vessels. (Dorland, 27th ed; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1646)Cell SeparationGenes, Insect: The functional hereditary units of INSECTS.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.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.Regenerative Medicine: A field of medicine concerned with developing and using strategies aimed at repair or replacement of damaged, diseased, or metabolically deficient organs, tissues, and cells via TISSUE ENGINEERING; CELL TRANSPLANTATION; and ARTIFICIAL ORGANS and BIOARTIFICIAL ORGANS and tissues.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.Alkaline Phosphatase: An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. EC 3.1.3.1.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.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Leukemia Inhibitory Factor: An INTERLEUKIN-6 related cytokine that exhibits pleiotrophic effects on many physiological systems that involve cell proliferation, differentiation, and survival. Leukemia inhibitory factor binds to and acts through the lif receptor.Smad2 Protein: A receptor-regulated smad protein that undergoes PHOSPHORYLATION by ACTIVIN RECEPTORS, TYPE I. It regulates TRANSFORMING GROWTH FACTOR BETA and ACTIVIN signaling.Antigens, Differentiation: Antigens expressed primarily on the membranes of living cells during sequential stages of maturation and differentiation. As immunologic markers they have high organ and tissue specificity and are useful as probes in studies of normal cell development as well as neoplastic transformation.Cell Division: The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.DNA Methylation: Addition of methyl groups to DNA. DNA methyltransferases (DNA methylases) perform this reaction using S-ADENOSYLMETHIONINE as the methyl group donor.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).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.Retinal Ganglion Cells: Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.Oogonia: Euploid female germ cells of an early stage of OOGENESIS, derived from primordial germ cells during ovarian differentiation. Oogonia undergo MEIOSIS and give rise to haploid OOCYTESMembrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Proto-Oncogene Proteins c-myc: Cellular DNA-binding proteins encoded by the c-myc genes. They are normally involved in nucleic acid metabolism and in mediating the cellular response to growth factors. Elevated and deregulated (constitutive) expression of c-myc proteins can cause tumorigenesis.Ovum: A mature haploid female germ cell extruded from the OVARY at OVULATION.Endodermal Sinus Tumor: An unusual and aggressive tumor of germ-cell origin that reproduces the extraembryonic structures of the early embryo. It is the most common malignant germ cell tumor found in children. It is characterized by a labyrinthine glandular pattern of flat epithelial cells and rounded papillary processes with a central capillary (Schiller-Duval body). The tumor is rarely bilateral. Before the use of combination chemotherapy, the tumor was almost invariably fatal. (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1189)beta Catenin: A multi-functional catenin that participates in CELL ADHESION and nuclear signaling. Beta catenin binds CADHERINS and helps link their cytoplasmic tails to the ACTIN in the CYTOSKELETON via ALPHA CATENIN. It also serves as a transcriptional co-activator and downstream component of WNT PROTEIN-mediated SIGNAL TRANSDUCTION PATHWAYS.Animals, Genetically Modified: ANIMALS whose GENOME has been altered by GENETIC ENGINEERING, or their offspring.Transgenes: Genes that are introduced into an organism using GENE TRANSFER TECHNIQUES.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Sex Differentiation: The process in developing sex- or gender-specific tissue, organ, or function after SEX DETERMINATION PROCESSES have set the sex of the GONADS. Major areas of sex differentiation occur in the reproductive tract (GENITALIA) and the brain.Flow Cytometry: Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.Cadherins: Calcium-dependent cell adhesion proteins. They are important in the formation of ADHERENS JUNCTIONS between cells. Cadherins are classified by their distinct immunological and tissue specificities, either by letters (E- for epithelial, N- for neural, and P- for placental cadherins) or by numbers (cadherin-12 or N-cadherin 2 for brain-cadherin). Cadherins promote cell adhesion via a homophilic mechanism as in the construction of tissues and of the whole animal body.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Promoter Regions, Genetic: DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.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.Coculture Techniques: A technique of culturing mixed cell types in vitro to allow their synergistic or antagonistic interactions, such as on CELL DIFFERENTIATION or APOPTOSIS. Coculture can be of different types of cells, tissues, or organs from normal or disease states.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.Epithelial Cells: Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Cell Count: The number of CELLS of a specific kind, usually measured per unit volume or area of sample.Pyramidal Cells: Projection neurons in the CEREBRAL CORTEX and the HIPPOCAMPUS. Pyramidal cells have a pyramid-shaped soma with the apex and an apical dendrite pointed toward the pial surface and other dendrites and an axon emerging from the base. The axons may have local collaterals but also project outside their cortical region.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.Neocortex: The largest portion of the CEREBRAL CORTEX in which the NEURONS are arranged in six layers in the mammalian brain: molecular, external granular, external pyramidal, internal granular, internal pyramidal and multiform layers.Intercellular Signaling Peptides and Proteins: Regulatory proteins and peptides that are signaling molecules involved in the process of PARACRINE COMMUNICATION. They are generally considered factors that are expressed by one cell and are responded to by receptors on another nearby cell. They are distinguished from HORMONES in that their actions are local rather than distal.RNA-Binding Proteins: Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA.Trans-Activators: Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.Infertility, Male: The inability of the male to effect FERTILIZATION of an OVUM after a specified period of unprotected intercourse. Male sterility is permanent infertility.Caenorhabditis elegans: A species of nematode that is widely used in biological, biochemical, and genetic studies.Nuclear Receptor Subfamily 6, Group A, Member 1: An orphan nuclear receptor expressed mainly in the GERM CELLS of GONADS. It functions as a transcription factor that binds to a direct repeat of the sequence AGGTCA and may play a role in the regulation of EMBRYOGENESIS and germ cell differentiation.
... possess two germ layers. Even simpler animals, such as sponges within the formally termed Porifera phylum, contain no true ... The germ layers form during gastrulation of the blastula. Additionally, the term may refer to any ovum in which the blastoderm ... Triploblasty is a condition of the blastula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm ... splits into three layers. All "higher" and "intermediate" animals, from flatworms to humans, arise from a triploblastic ovum. ...
2008). "Animals Based on Three Germ Layers and a Coelem". Strickberger's evolution: the integration of genes, organisms and ... A pseudocoelomate or blastocoelomate is any invertebrate animal with a three-layered body and a pseudocoel. The coelom was ... In developed animals, it is lined with a mesodermal epithelium. In other animals, such as molluscs, it remains undifferentiated ... Pseudocoelomate animals are also referred to as Hemocoel and Blastocoelomate. Acoelomate animals, like flatworms, have no body ...
A germ layer is a collection of cells, formed during animal and mammalian embryogenesis. Germ layers are typically pronounced ... Animals with bilateral symmetry produce a third layer in-between called mesoderm, making them triploblastic. Germ layers will ... The mesoderm germ layer forms in the embryos of animals and mammals more complex than cnidarians, making them triploblastic. ... The endoderm is one of the germ to penes layers formed during animal embryogenesis. Cells migrating inward along the ...
The germ layers are referred to as the ectoderm, mesoderm and endoderm. In diploblastic animals only the ectoderm and the ... For many mammals, it is sometime during formation of the germ layers that implantation of the embryo in the uterus of the ... In most animals, a blastopore is formed at the point where cells are entering the embryo. Two major groups of animals can be ... At some point after the different germ layers are defined, organogenesis begins. The first stage in vertebrates is called ...
Establishing three germ layers during gastrulation is another critical step in animal development. Each of the three germ ... Establishing body axes is a critical step in animal development. During mouse embryonic development, Nodal, a transforming ... Pigmentation patterns provide one of the most striking and easily scored differences between different species of animals. ... S. "Identifying transcriptional cis ‐regulatory modules in animal genomes". WIREs Dev Biol. 4 (2014): 59-84. doi:10.1002/wdev. ...
All of a triploblastic animal's tissues and organs are derived from the three germ layers of the embryo, the ectoderm, mesoderm ... All of the different cells of an animal are derived from the embryonic germ layers. Those simpler invertebrates which are ... formed from two germ layers of ectoderm and endoderm are called diploblastic and the more developed animals whose structures ... In simple animals this may just be a coat of glycoproteins. In more advanced animals, many glands are formed of epithelial ...
For the most part, bilateral embryos are triploblastic, having three germ layers: endoderm, mesoderm, and ectoderm. Nearly all ... The Invertebrate Animals Helfenbein, Kevin G.; Fourcade, H. Matthew; Vanjani, Rohit G.; Boore, Jeffrey L. (20 July 2004). "The ... Nielsen, C. (2002). Animal Evolution: Interrelationships of the Living Phyla (2nd ed.). England: Oxford University Press. ISBN ... In contrast, radially symmetrical animals like jellyfish have a topside and a downside, but no identifiable front or back. The ...
The way the germ layers themselves developed is disputed. Eumetazoa are a very similar proposed clade, but they traditionally ... In a study of basal animals, the porifera were found to the basalmost extant animals, resulting in the cladogram below. It is ... They feature diploblasty, i.e. they have two germ layers. Basal Diploblasts are the Ctenophora and the ParaHoxozoa, which, ... The resolvement of the emergence of the triploblasts and other basal animals in the diploblast tree is still controversial, as ...
Simpler animals, such as sea sponges, have one germ layer and lack true tissue organization. All the more complex animals (from ... Diploblasty is a condition of the blastula in which there are two primary germ layers: the ectoderm and endoderm. Diploblastic ... are triploblastic with three germ layers (a mesoderm as well as ectoderm and endoderm). The mesoderm allows them to develop ... Groups of diploblastic animals alive today include jellyfish, corals, sea anemones and comb jellies. Triploblasty. ...
The cellular tissues that ultimately become teeth originate from the embryonic germ layer, the ectoderm. The general structure ... When the animal reaches old age, the crowns of the teeth are very short and the teeth are often lost altogether. Very old ... whales have cementum on the entire surface of the tooth with a very small layer of enamel at the tip. This small enamel layer ... Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are covered by ...
Organoid Ectoderm Embryogenesis Endoderm Eye development Gastrulation Germ layer Germ line development Gonadogenesis Heart ... In animal development, organogenesis (organo-genesis, compound of the Greek words όργανον "that with which one works", and ... The germ layers in organogenesis differ by three processes: folds, splits, and condensation. Developing early during this stage ... Vertebrate animals all differentiate from the gastrula the same way. Vertebrates develop a neural crest that differentiates ...
In all bilaterian animals, the mesoderm is one of the three primary germ layers in the very early embryo. The other two layers ... The visceral layer forms the walls of the gut tube. Mesoderm cells of the parietal layer form the mesothelial membranes or ... The somatic layer depends on a continuous layer with mesoderm that covers the amnion. The splanchnic depends on a continuous ... The two layers cover the intraembryonic cavity. The parietal layer together with overlying ectoderm forms the lateral body wall ...
Within S. argyrosperma the oscules are inconspicuous.2 Sponges have no true tissues or germ layers. While the cells are loosely ... Also, because of being a susceptible and responsive freshwater animal, Spongilla species are potentially very valuable ... organized, different cells are responsible for different functions within the animal but have the ability to transform into ...
The mesoderm forms at the same time as the other two germ layers, the ectoderm and endoderm. The mesoderm at either side of the ... A somite is a division of the body of an animal or embryo. Somites are bilaterally paired blocks of paraxial mesoderm that form ... The myotome is that part of a somite that forms the muscles of the animal. Each myotome divides into an epaxial part (epimere ... In this definition, the somite is a homologously paired structure in an animal body plan, such as is visible in annelids and ...
... which include humans and many other animals. It is an embryo which exists as three different germ layers - the ectoderm, the ... These layers are arranged on top of each other like a stack of paper, giving rise to the name trilaminar, or "three-layered". ... A trilaminar embryo (or trilaminary blastoderm, or trilaminar germ disk) is an early stage in the development of triploblastic ... These three layers arise early in the third week (after gastrulation) from the epiblast (a portion of the mammalian inner cell ...
Animal structure is described by its body plan, which encompasses the body symmetry, the type of germ layers and of body ... Habitat Animal migration Habit (psychology) Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Derivation and ... The habits of plants and animals often change in response to changes in their environment. For example: if a species develops a ... "Disease May Help Shape Animals' Migration Habits". Retrieved 17 May 2013. The Columbia Encyclopedia, Sixth Edition. 2001-05 ...
The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. ... both to describe the organs of plants or animals (e.g. the roots of a tree, the heart or liver of an animal), and to describe ... Complex animals are composed of organs and many of these organs evolved a very long time ago. For example, the liver evolved in ... Historically, viscera of animals were examined by Roman pagan priests like the haruspices or the augurs in order to divine the ...
... mostly comprising animals with bilateral symmetry and three germ layers. The major distinctions between deuterostomes and ... In animals at least as complex as earthworms, the embryo forms a dent on one side, the blastopore, which deepens to become the ... Animal Evolution - Genomes, Fossils, and Trees. pp. 33-40. CS1 maint: Uses editors parameter (link) Martín-Durán, José M.; ... Animal Evolution - Genomes, Fossils, and Trees. pp. 33-40. CS1 maint: Uses editors parameter (link) Dawkins, Richard. The ...
It is the animal hemisphere of the blastula that will eventually become the ectoderm. Like the other two germ layers, mesoderm ... Ectoderm is one of the three primary germ layers in the very early embryo. The other two layers are the mesoderm (middle layer ... The once superficial cells of the animal pole are destined to become the cells of the middle germ layer called the mesoderm. ... Baer published his findings, including his germ layer theory, in a textbook which translates to On the Development of Animals ...
... whose tissues are organized into Germ layers; chancellorids' lack of organs such as sense organs, muscles and a gut would seem ... It is thought that when the animals were alive these cavities were filled with tissues that secreted the hard outer coverings. ... The Chancelloriids are an extinct family of animal common in sediments from the Early Cambrian to the early Late Cambrian. Many ... Bengtson, S. "Mineralized skeletons and early animal evolution". In Briggs, D.E.G. Evolving form and function: fossils and ...
"Germ Layers and the Germ-Layer Theory Revisited: Primary and Secondary Germ Layers, Neural Crest as a Fourth Germ Layer, ... debate on the nature and mechanisms of animal body plan formation. Professor Hall has proposed that the neural crest tissue of ... It addresses the role of the germ layers in early embryogenesis, the development of nervous systems, and the evolution of the ... and Demise of the Germ-Layer Theory", in Max K. Hecht; Ross J. MacIntyre; Michael T. Clegg, Evolutionary Biology, 30, New York ...
... is found in the germ and aleurone layer of grains, and milling results in the reduction of this vitamin in white ... With the capacity for absorption being so great, animals are able to absorb quantities much greater than necessary for ... which is far more stable than the pyridoxal or pyridoxamine found in animal foods. For example, milk can lose 30-70% of its ...
There are only two main germ layers, the ectoderm and endoderm, with only scattered cells between them. As such, they are ... The former, which is the second-largest animal phylum by number of described species, includes animals such as snails, clams, ... The majority of animal species are invertebrates; one estimate puts the figure at 97%. Many invertebrate taxa have a greater ... Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a backbone or spine), derived ...
In some cases, the animal pole is thought to differentiate into the later embryo itself, forming the three primary germ layers ... The development of the animal-vegetal axis occurs prior to fertilization. Sperm entry can occur anywhere in the animal ... The animal pole draws its name from its liveliness relative to the slowly developing vegetal pole. Hence the vegetal pole is ... The animal hemisphere is dark brown, and the vegetal hemisphere is only weakly pigmented. The axis of symmetry passes through ...
Characteristics of eumetazoans include true tissues organized into germ layers, the presence of neurons, and an embryo that ... 2005 Metazoa: the Animals Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla, 2nd edition, 563 pp. ... comprising a revision of speculations relative to the origin and significance of the germ-layers. Quartely Journal of ... The discoverers of Vernanimalcula describe it as the fossil of a bilateral triploblastic animal that appeared at the end of the ...
This three-layered covering is composed of (from the outside in) the dura mater ("hard mother"), arachnoid mater ("spidery ... Less commonly, and seen usually in infants, are teratomas and atypical teratoid rhabdoid tumors.[65] Germ cell tumors, ... technology to in vivo models of cancer and in 2005 reported a long-term survival benefit in an experimental brain tumor animal ... Echevarría ME, Fangusaro J, Goldman S (June 2008). "Pediatric central nervous system germ cell tumors: a review". Oncologist. ...
In particular we study their role during gastrulation, the time when the germ layers are separated. Three "mesodermal" genes, ... In animal kingdom, miRNAs have been identified in protostomes and veterbrates so far. Thus, miRNA information from other animal ... in term of animals density per beaker and fecundity, compare to our actual culture standard (100-110 animals per 6L beaker, 300 ... The Xenopus animal cap assay, was used to compare the activity of the Hydra Brachyury paralogues with the endogenous orthologue ...
Use the chart and reading passage in this science printable to identify the embryo germ layer endoderm, mesoderm, or ectoderm ... How Do Animal Embryos Develop? After matching terms and answering questions about animal reproduction, students will make a bar ... Use the chart and reading passage in this science printable to identify the embryo germ layer endoderm, mesoderm, or ectoderm ...
When differentiated as aggregates, wild-type mESCs form descendants of all three germ layers, whereas mesendodermal germ layer ... Differential requirement for the dual functions of β-catenin in embryonic stem cell self-renewal and germ layer formation Nat ...
The First Animals: - Sponges by Aleena Sallot , This newsletter was created with Smore, an online tool for creating beautiful ... Germ Layers Only have 1 germ layer. Symmetry A sponge has either radial symmetry or is asymmetrical. ... http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/animal%20diversity/lower% ... http://adapaproject.org/bbk/tiki-index.php?page=Leaf%3A+What+are+animals%3F ...
The First Animal - Sponges by Kaley Fulk , This newsletter was created with Smore, an online tool for creating beautiful ...
Triploblasts, Bilaterally symmetrical animals with three germ layers. Click on an image to view larger version & data in a new ... Triploblasts, Bilaterally symmetrical animals with three germ layers. The TEXT of this page is licensed under the Creative ... Triploblasts, Bilaterally symmetrical animals with three germ layers. Version 01 January 2002 (temporary). http://tolweb.org/ ... Testing the new animal phylogeny: A phylum level molecular analysis of the animal kingdom. Molecular Phylogenetics and ...
... produce two or three primary germ layers. Animals with radial symmetry, like cnidarians, produce two germ layers (the ectoderm ... A germ layer is a primary layer of cells that form during embryogenesis. The three germ layers in vertebrates are particularly ... The top layer is now called the ectoderm. The endoderm is one of the germ layers formed during animal embryogenesis. Cells ... Animals with bilateral symmetry produce a third layer (the mesoderm), between these two layers. making them triploblastic. Germ ...
True tissues are present in Cnidaria, flatworms, and all higher animals. Number of Embryonic Germ Layers[edit]. Germ layers are ... Two Germ Layers[edit]. Organisms with two germ layers are said to be diploblastic. ... Three Germ Layers[edit]. Such organisms are said to be triploblastic. This is characteristic of flatworms and all higher ... Four Germ Layers (?)[edit]. Some developmental biologists consider the neural crest tissue of vertebrate embryos to be a fourth ...
Find answers for What Are The Three Types Of Germ Layers That Form Tissues And Organs In Animals of Embryology and participate ... The three germ layers are the ectoderm, the mesoderm, and the endoderm.Image Diversity: germ layers ... What Are The Three Types Of Germ Layers That Form Tissues And Organs In Animals. Write a Reply. ... What Are The Three Types Of Germ Layers That Form Tissues And Organs In Animals ...
... and the bigger one was connected to the serosa layer of the small intestine of the animal, as it was evidenced by microscopic ... Development of Some Organs Derived from the Three Embryonic Germ Layer in a Degus Ectopic Pregnancy and Presence of a ... Histologically, the masses consisted of tissues derived from all three embryonic germ layers, but appendages of the skin were ... Histologically, the masses consisted of various tissues derived from all three embryonic germ layers, that is, ectoderm ( ...
2008). "Animals Based on Three Germ Layers and a Coelem". Strickbergers evolution: the integration of genes, organisms and ... A pseudocoelomate or blastocoelomate is any invertebrate animal with a three-layered body and a pseudocoel. The coelom was ... In developed animals, it is lined with a mesodermal epithelium. In other animals, such as molluscs, it remains undifferentiated ... Pseudocoelomate animals are also referred to as Hemocoel and Blastocoelomate. Acoelomate animals, like flatworms, have no body ...
Members of the phylum Chordata have three main germ cell layers, each with its own unique role in development. In this lesson, ... To best understand how germ layers contribute to the growth and development of a chordate, or an animal possessing a ... What Is a Germ Layer?. In spite of the name, germ layers have nothing to do with germs or getting sick. A germ layer is a layer ... Each germ layer interacts with the adjacent layer as the embryo grows, and each germ layer contributes to the formation of all ...
A germ layer is a collection of cells, formed during animal embryogenesis. Germ layers are only really pronounced in the ... A germ layer is a collection of cells, formed during animal embryogenesis. Germ layers are only really pronounced in the ... Animals with bilateral symmetry produce a third layer in-between called mesoderm, making them triploblastic. Germ layers will ... produce two or three primary tissue layers (sometimes called primary germ layers). Animals with radial symmetry, like ...
9780781733588 Our cheapest price for Anatomy and Physiology of Farm Animals, 6th Edition is $2.51. Free shipping on all orders ... Development of Germ Layers. 47. (2). Neurulation. 49. (1). Differentiation of Other Tissues. ... placing Anatomy and Physiology of Farm Animals among the most widely accepted resources available to the veterinary, animal ... Anatomy and Physiology of Farm Animals, 6th Edition. by Frandson, Rowen D.; Wilke, W. Lee; Fails, Anna Dee *ISBN13: ...
Germ layers[change , change source]. Among animals, sponges show the simplest organization, having a single germ layer. ... Development of germ layers[change , change source]. The purpose of gastrulation is to position the 3 embryonic germ layers, the ... Cnidaria and ctenophores show an increase in complexity, having two germ layers, the endoderm and ectoderm. All higher animals ... Gastrulation of a diploblast: The formation of germ layers from a (1) sphere of cells (the blastula) to a (2) gastrula. Some of ...
These germ layers then differentiate to form tissues and organs.[35]. Food and energy sourcing. Main article: Animal nutrition ... Animals can be divided into two broad groups: vertebrates (animals with a backbone) and invertebrates (animals without a ... There are only two main germ layers, the ectoderm and endoderm, with only scattered cells between them. As such, these animals ... "Animal". The American Heritage Dictionary (4th ed.). Houghton Mifflin Company. 2006.. *^ "Animals". Merriam-Websters. ...
The three primary germ layers will be established.. All tissues and organs will come from these germ layers.. The primitive gut ... Fates of the three primary germ layers (learn this!) Urchin Larvae How does a multicellular organism develop from a zygote?. ... How does differentiation of cell type occur in animals? Big Questions Can You Explain the major phases of animal development.. ... Transcript of Animal Development. Development Overview Animal Development occurs in stages. Development continues unti maturity ...
The three primary germ layers will be established.. All tissues and organs will come from these germ layers.. The primitive gut ... Development Animals Plants Overview Animal Development occurs in stages. Development continues after birth, until maturity ... Gastrulation in Sea Urchins Gastrulation in Frogs Fates of the three primary germ layers (learn this!) Just Think Layers ... How is the development of an animal different from the development of a plant? How are they similar?. How is the position ( ...
We report an induction process occurring between two germ layers in the Drosophila embryo that involves a cascade of five ... Animals * Cell Differentiation* * Drosophila melanogaster / embryology* * Drosophila melanogaster / genetics * Embryonic ... Induction across germ layers in Drosophila mediated by a genetic cascade Cell. 1990 Jul 27;62(2):261-8. doi: 10.1016/0092-8674( ... We report an induction process occurring between two germ layers in the Drosophila embryo that involves a cascade of five ...
Introduction to the Animal Kingdom: Origin and Evolution, Classification, Body Features, Embryology and Phylogeny. Warm Ups, ... Introduction to the Animal Kingdom: Origin and Evolution, Classification, Body Features, Embryology and Phylogeny. Warm Ups, ... The animal body plan: symmetry, radial symmetry, bilateral symmetry, dorsal, ventral, posterior, anterior, germ layers, body ... More About Animals!. • Origin and Classification of Animals. • Phyla of the Animal Kingdom. • Body Structures of Animals. • ...
All of the different cells of an animal are derived from the embryonic germ layers. Those simpler invertebrates which are ... All of a triploblastic animals tissues and organs are derived from the three germ layers of the embryo, the ectoderm, mesoderm ... formed from two germ layers of ectoderm and endoderm are called diploblastic and the more developed animals whose structures ... In simple animals this may just be a coat of glycoproteins.[13] In more advanced animals, many glands are formed of epithelial ...
DIFFERENTIATION OF GERM LAYERS. 3. Gametogenesis. • Mitosis/Meiosis. • Oogenesis. • Spermatogenesis. • Veterinary Clinical ... Essentials of Domestic Animal Embryology - Elsevier eBook on VitalSource (Retail Access Card), ... Poul Hyttel, DVM, PhD, DVSc, Professor, Department of Basic Animal and Veterinary Sciences, Faculty of Life Sciences, ... Species Variations Effecting Gestation Length: Companion, Domestic, Wildlife and Laboratory Animals. • Reproductive Cycles: ...
The cells of most animal embryos differentiate into the three layers called germ layers ... Advanced animals have body segments and specialization of tissue.. Ex humans with ribs and spine ... Most animals are motile (can move) in one stage of their life ... Very small animals rely on diffusion. Large animals have ... The body plan of an animal, how its body parts are arranged ... The more complex the animals become the more pronounced their ...
Forms 3 germ layers by process of gastrulation. Germ layers form embryo and some of extra embryonic membranes ... Animals have diploid number of chromosomes in their somatic cells. 2N. Diploid cells have homologous pairs of chromosomes one ... Feminization of animal due to increased estrogen production, alopecia. Mammary gland growth, atrophy of penis, pendulous ... Myometrium: layers of smooth muscle. Endometrium: similar columnar epithelium with simple tubular glands, blood vessels. ...
Diploblastic Organisms - Animals with two germ layers 16. Phylum Porifera 16. Symplasma* - Class Hexactinellida 16. Cellularia ... Gastrulation, second germ layer formation 12. Mesoderm, third germ layer formation 13. Organ differentiation 13. Larvae 13. ... Triploblastic Organisms - Animals with three germ layers 7. Archicoelomata 7. Phylum Hemichordata 7. Class Enteropneusta 8. ... Ancestral mode of ontogeny in diploblastic animals 127. Cleavage pattern 127. Gastrulation 127. Second germ layer hypothesis ...
  • Although scientifically humans are animals, in everyday usage, animal often refers to any member of the animal kingdom that is not a human being , and sometimes excludes insects (although including such arthropods as crabs). (newworldencyclopedia.org)
  • The common distinction made between animals and humans likely reflects the special status people accord themselves as the pinnacle of the natural world, and indeed stewards of creation, and the fact that humans also are defined in religious, spiritual, moral, social, and psychological terms. (newworldencyclopedia.org)
  • The kingdom Animalia includes humans , but in colloquial use the term animal often refers only to non-human animals. (wikipedia.org)
  • We conclude that, compared with heterochronic parabiosis, heterochronic blood exchange in small animals is less invasive and enables better-controlled studies with more immediate translation to therapies for humans. (nature.com)
  • b)Radial-This type of animal is divisible into two equal halves by any plane that passes through the centre from top to the bottom e.g. (expertsmind.com)
  • The body wall of Porifera consists mainly of two layers, pinacoderm and choanoderm, and a non-cellular structure between these two layes called mesohyl. (wikipedia.org)
  • He has spent decades, first in Europe and then at the Salk Institute in the U.S., tracing the genetic and developmental steps that allow these animals to regenerate legs and fins, among other things. (scientificamerican.com)
  • But the lab has made up for the rocky start with a series of surprising discoveries that have begun to shed light on the fundamental principles of animal regeneration-revealing the remarkable developmental plasticity that allows these animals to regrow their heads, their tails, and everything in between. (the-scientist.com)
  • He is an active participant in the evolutionary developmental biology (EVO-DEVO) debate on the nature and mechanisms of animal body plan formation. (xenbase.org)
  • Current developmental biology shows that animals follow similar developmental programs, but do not go through a "species change" during development. (edu.au)
  • The epiblast in this region moves towards the primitive streak, dives down into it, and forms a new layer, called the endoderm, pushing the hypoblast out of the way (this goes on to form the amnion. (wikipedia.org)
  • You'll remember these layers are called the endoderm, or the inside derm, and the ectoderm, or the outside derm, and they form a tube that allows an animal to ingest, digest, and get rid of stuff. (khanacademy.org)
  • Using a method called CEL-Seq that can spy on the activity of every gene within a cell at once, Technion Associate Professor Itai Yanai and his colleagues now provide compelling evidence that the layer called the endoderm evolved first, followed by the ectoderm layer and finally the mesoderm layer. (phys.org)
  • Evidence that this segment polarity network might be conserved is primarily based on the expression patterns of en , wg , and more recently, Hh pathway component genes in other insects as well as non-insect arthropods and annelids (Patel et al. (springer.com)
  • The course will examine the structure and function of animal organ systems in the framework of the evolution of adaptations. (rmu.edu)