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.
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.
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.
Pluripotent Stem Cells
Cells that can give rise to cells of the three different GERM LAYERS.
Cell Differentiation
Embryo, Mammalian
Induced Pluripotent Stem Cells
Cells from adult organisms that have been reprogrammed into a pluripotential state similar to that of EMBRYONIC STEM CELLS.
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.
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.
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.
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.
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.
Cell Lineage
The developmental history of specific differentiated cell types as traced back to the original STEM CELLS in the embryo.
Neural Stem Cells
Self-renewing cells that generate the main phenotypes of the nervous system in both the embryo and adult. Neural stem cells are precursors to both NEURONS and NEUROGLIA.
Stem Cell Niche
A particular zone of tissue composed of a specialized microenvironment where stem cells are retained in a undifferentiated, self-renewable state.
Hematopoietic Stem Cell Transplantation
Transfer of HEMATOPOIETIC STEM CELLS from BONE MARROW or BLOOD between individuals within the same species (TRANSPLANTATION, HOMOLOGOUS) or transfer within the same individual (TRANSPLANTATION, AUTOLOGOUS). Hematopoietic stem cell transplantation has been used as an alternative to BONE MARROW TRANSPLANTATION in the treatment of a variety of neoplasms.
Gene Expression Regulation, Developmental
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)
Cells, Cultured
Embryo Implantation
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.
Mesenchymal Stromal Cells
Bone-marrow-derived, non-hematopoietic cells that support HEMATOPOETIC STEM CELLS. They have also been isolated from other organs and tissues such as UMBILICAL CORD BLOOD, umbilical vein subendothelium, and WHARTON JELLY. These cells are considered to be a source of multipotent stem cells because they include subpopulations of mesenchymal stem cells.
Mesenchymal Stem Cell Transplantation
Transfer of MESENCHYMAL STEM CELLS between individuals within the same species (TRANSPLANTATION, HOMOLOGOUS) or transfer within the same individual (TRANSPLANTATION, AUTOLOGOUS).
Totipotent Stem Cells
Single cells that have the potential to form an entire organism. They have the capacity to specialize into extraembryonic membranes and tissues, the embryo, and all postembryonic tissues and organs. (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)
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.
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.
Stem Cell Factor
A hematopoietic growth factor and the ligand of the cell surface c-kit protein (PROTO-ONCOGENE PROTEINS C-KIT). It is expressed during embryogenesis and is a growth factor for a number of cell types including the MAST CELLS and the MELANOCYTES in addition to the HEMATOPOIETIC STEM CELLS.
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)
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).
Cell Proliferation
All of the processes involved in increasing CELL NUMBER including CELL DIVISION.
Germ Layers
Stem Cell Research
Embryo, Nonmammalian
The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.
Fertilization in Vitro
An assisted reproductive technique that includes the direct handling and manipulation of oocytes and sperm to achieve fertilization in vitro.
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.
Transcription Factors
Gene Expression Profiling
Cloning, Organism
Pregnancy
Endoderm
The inner of the three germ layers of an embryo.
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.
Beginning of Human Life
The point at which religious ensoulment or PERSONHOOD is considered to begin.
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.
Personhood
The state or condition of being a human individual accorded moral and/or legal rights. Criteria to be used to determine this status are subject to debate, and range from the requirement of simply being a human organism to such requirements as that the individual be self-aware and capable of rational thought and moral agency.
Fetal Stem Cells
Cells derived from a FETUS that retain the ability to divide, proliferate and 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.
Cell Separation
Reverse Transcriptase Polymerase Chain Reaction
Base Sequence
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.
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.
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.
Embryo Disposition
Plant Stems
Mice, Inbred C57BL
Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.
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.
Hematopoiesis
The development and formation of various types of BLOOD CELLS. Hematopoiesis can take place in the BONE MARROW (medullary) or outside the bone marrow (HEMATOPOIESIS, EXTRAMEDULLARY).
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.
Gene Targeting
The integration of exogenous DNA into the genome of an organism at sites where its expression can be suitably controlled. This integration occurs as a result of homologous recombination.
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.
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.
Gene Expression Regulation
Neoplastic Stem Cells
Highly proliferative, self-renewing, and colony-forming stem cells which give rise to NEOPLASMS.
Phenotype
Green Fluorescent Proteins
Immunohistochemistry
Gene Expression
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.
Mesoderm
Models, Biological
Neurons
Bone Marrow Cells
Cells contained in the bone marrow including fat cells (see ADIPOCYTES); STROMAL CELLS; MEGAKARYOCYTES; and the immediate precursors of most blood cells.
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.
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.
Hematopoietic Stem Cell Mobilization
The release of stem cells from the bone marrow into the peripheral blood circulation for the purpose of leukapheresis, prior to stem cell transplantation. Hematopoietic growth factors or chemotherapeutic agents often are used to stimulate the mobilization.
Karyotyping
Mapping of the KARYOTYPE of a cell.
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.
Cell Survival
Embryo Transfer
The transfer of mammalian embryos from an in vivo or in vitro environment to a suitable host to improve pregnancy or gestational outcome in human or animal. In human fertility treatment programs, preimplantation embryos ranging from the 4-cell stage to the blastocyst stage are transferred to the uterine cavity between 3-5 days after FERTILIZATION IN VITRO.
Mice, Transgenic
Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.
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.
Cell- and Tissue-Based Therapy
Fibroblasts
Tissue Engineering
Myocytes, Cardiac
DNA-Binding Proteins
Blastocyst Inner Cell Mass
The cluster of cells inside a blastocyst. These cells give rise to the embryonic disc and eventual embryo proper. They are pluripotent EMBRYONIC STEM CELLS capable of yielding many but not all cell types in a developing organism.
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.
Antigens, CD34
Cell Division
The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.
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.
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.
Nestin
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.
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.
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.
Colony-Forming Units Assay
A cytologic technique for measuring the functional capacity of stem cells by assaying their activity.
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.
Oligonucleotide Array Sequence Analysis
Hybridization of a nucleic acid sample to a very large set of OLIGONUCLEOTIDE PROBES, which have been attached individually in columns and rows to a solid support, to determine a BASE SEQUENCE, or to detect variations in a gene sequence, GENE EXPRESSION, or for GENE MAPPING.
Nuclear Transfer Techniques
Methods of implanting a CELL NUCLEUS from a donor cell into an enucleated acceptor cell.
Genetic Vectors
DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.
Transcription, Genetic
Amino Acid Sequence
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.
Mutation
Trophoblasts
Cells lining the outside of the BLASTOCYST. After binding to the ENDOMETRIUM, trophoblasts develop into two distinct layers, an inner layer of mononuclear cytotrophoblasts and an outer layer of continuous multinuclear cytoplasm, the syncytiotrophoblasts, which form the early fetal-maternal interface (PLACENTA).
Preimplantation Diagnosis
Determination of the nature of a pathological condition or disease in the OVUM; ZYGOTE; or BLASTOCYST prior to implantation. CYTOGENETIC ANALYSIS is performed to determine the presence or absence of genetic disease.
Culture Media, Conditioned
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.
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).
Antigens, CD15
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.
Transplantation, Autologous
Neurogenesis
Formation of NEURONS which involves the differentiation and division of STEM CELLS in which one or both of the daughter cells become neurons.
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).
Transplantation, Homologous
Promoter Regions, Genetic
Peripheral Blood Stem Cell Transplantation
Transplantation of stem cells collected from the peripheral blood. It is a less invasive alternative to direct marrow harvesting of hematopoietic stem cells. Enrichment of stem cells in peripheral blood can be achieved by inducing mobilization of stem cells from the BONE MARROW.
Fetus
The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.
Cell Transplantation
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.
Culture Media, Serum-Free
CULTURE MEDIA free of serum proteins but including the minimal essential substances required for cell growth. This type of medium avoids the presence of extraneous substances that may affect cell proliferation or unwanted activation of cells.
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.
Mosaicism
Cell Count
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.
Ectoderm
The outer of the three germ layers of an embryo.
DNA Methylation
In Situ Hybridization
Polymerase Chain Reaction
In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.
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.
Pregnancy Rate
Clone Cells
A group of genetically identical cells all descended from a single common ancestral cell by mitosis in eukaryotes or by binary fission in prokaryotes. Clone cells also include populations of recombinant DNA molecules all carrying the same inserted sequence. (From King & Stansfield, Dictionary of Genetics, 4th ed)
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.
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.
Histones
Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.
Life
The state that distinguishes organisms from inorganic matter, manifested by growth, metabolism, reproduction, and adaptation. It includes the course of existence, the sum of experiences, the mode of existing, or the fact of being. Over the centuries inquiries into the nature of life have crossed the boundaries from philosophy to biology, forensic medicine, anthropology, etc., in creative as well as scientific literature. (Random House Unabridged Dictionary, 2d ed; Dr. James H. Cassedy, NLM History of Medicine Division)
Cell Cycle
The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.
Cell Movement
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.
Apoptosis
One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
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.
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.
Proto-Oncogene Proteins c-kit
A protein-tyrosine kinase receptor that is specific for STEM CELL FACTOR. This interaction is crucial for the development of hematopoietic, gonadal, and pigment stem cells. Genetic mutations that disrupt the expression of PROTO-ONCOGENE PROTEINS C-KIT are associated with PIEBALDISM, while overexpression or constitutive activation of the c-kit protein-tyrosine kinase is associated with tumorigenesis.
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.
HMGB Proteins
MicroRNAs
Small double-stranded, non-protein coding RNAs, 21-25 nucleotides in length generated from single-stranded microRNA gene transcripts by the same RIBONUCLEASE III, Dicer, that produces small interfering RNAs (RNA, SMALL INTERFERING). They become part of the RNA-INDUCED SILENCING COMPLEX and repress the translation (TRANSLATION, GENETIC) of target RNA by binding to homologous 3'UTR region as an imperfect match. The small temporal RNAs (stRNAs), let-7 and lin-4, from C. elegans, are the first 2 miRNAs discovered, and are from a class of miRNAs involved in developmental timing.
Genes, Reporter
Genes whose expression is easily detectable and therefore used to study promoter activity at many positions in a target genome. In recombinant DNA technology, these genes may be attached to a promoter region of interest.
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.
Antigens, CD
Differentiation antigens residing on mammalian leukocytes. CD stands for cluster of differentiation, which refers to groups of monoclonal antibodies that show similar reactivity with certain subpopulations of antigens of a particular lineage or differentiation stage. The subpopulations of antigens are also known by the same CD designation.
Nerve Tissue Proteins
'Nerve tissue proteins' are specialized proteins found within the nervous system's biological tissue, including neurofilaments, neuronal cytoskeletal proteins, and neural cell adhesion molecules, which facilitate structural support, intracellular communication, and synaptic connectivity essential for proper neurological function.
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.
Blotting, Western
Basic Helix-Loop-Helix Transcription Factors
A family of DNA-binding transcription factors that contain a basic HELIX-LOOP-HELIX MOTIF.
Spheroids, Cellular
Spherical, heterogeneous aggregates of proliferating, quiescent, and necrotic cells in culture that retain three-dimensional architecture and tissue-specific functions. The ability to form spheroids is a characteristic trait of CULTURED TUMOR CELLS derived from solid TUMORS. Cells from normal tissues can also form spheroids. They represent an in-vitro model for studies of the biology of both normal and malignant cells. (From Bjerkvig, Spheroid Culture in Cancer Research, 1992, p4)
Transduction, Genetic
The transfer of bacterial DNA by phages from an infected bacterium to another bacterium. This also refers to the transfer of genes into eukaryotic cells by viruses. This naturally occurring process is routinely employed as a GENE TRANSFER TECHNIQUE.
Anatomy, Artistic
RNA Interference
A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.
Mice, Inbred NOD
GATA6 Transcription Factor
A GATA transcription factor that is expressed predominately in SMOOTH MUSCLE CELLS and regulates vascular smooth muscle CELL DIFFERENTIATION.
Theology
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.
Sperm Injections, Intracytoplasmic
Transfection
The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.
Aneuploidy
The chromosomal constitution of cells which deviate from the normal by the addition or subtraction of CHROMOSOMES, chromosome pairs, or chromosome fragments. In a normally diploid cell (DIPLOIDY) the loss of a chromosome pair is termed nullisomy (symbol: 2N-2), the loss of a single chromosome is MONOSOMY (symbol: 2N-1), the addition of a chromosome pair is tetrasomy (symbol: 2N+2), the addition of a single chromosome is TRISOMY (symbol: 2N+1).
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).
Embryology
The study of the development of an organism during the embryonic and fetal stages of life.
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)
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.
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.
Incubators
Antigens, Differentiation
Cryoprotective Agents
Stromal Cells
Connective tissue cells of an organ found in the loose connective tissue. These are most often associated with the uterine mucosa and the ovary as well as the hematopoietic system and elsewhere.
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.
DNA, Complementary
Chondrogenesis
Tissue Scaffolds
Cell growth support structures composed of BIOCOMPATIBLE MATERIALS. They are specially designed solid support matrices for cell attachment in TISSUE ENGINEERING and GUIDED TISSUE REGENERATION uses.
Hematopoietic System
X Chromosome Inactivation
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)
Mice, Inbred Strains
Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.
In Situ Hybridization, Fluorescence
A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.