Glossary


Allele.

Individual variation in a particular gene.

Alloimmune thrombocytopenia.

A fetal disorder in which the mother's immune system makes antibodies against the blood platelets of the fetus.

Amniocentesis.

Prenatal testing method in which fluid from the sac surrounding the fetus (amniotic sac) is analyzed for sex determination and for genetic and biochemical properties.

Aneuploidy.

Presence of abnormal numbers of chromosomes.

Antibody.

B-lymphocyte receptor dispatched by the cell into body fluids that recognizes and binds to cell-surface proteins on foreign cells.

Antigen.

Cell-surface protein on an infectious agent, cancer cell, or cell of another organism that marks it as foreign.

Axon.

Long, slender extensions of neurons down which neuronal electrical impulses travel, culminating in the release of neurotransmitter across the synapse to a target cell.


B lymphocytes, or B cells.

Specialized cells of the immune system, products of hematopoiesis, that release antibodies.

Blastomere.

One of the cells resulting from division of the fertilized ovum.


Cerebral cortex.

Multilayered sheet of neurons that covers the cerebral hemispheres of the brain and coordinates and controls many functions including sensation, movement, and cognition.

Chorionic villi sampling (CVS).

Prenatal testing method in which fetal cells are aspirated from early placenta (villi) and analyzed for genetic abnormalities.

Cryopreservation.

Preservation of biological tissue by freezing.



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Fetal Research and Applications: A Conference Summary Glossary Allele. Individual variation in a particular gene. Alloimmune thrombocytopenia. A fetal disorder in which the mother's immune system makes antibodies against the blood platelets of the fetus. Amniocentesis. Prenatal testing method in which fluid from the sac surrounding the fetus (amniotic sac) is analyzed for sex determination and for genetic and biochemical properties. Aneuploidy. Presence of abnormal numbers of chromosomes. Antibody. B-lymphocyte receptor dispatched by the cell into body fluids that recognizes and binds to cell-surface proteins on foreign cells. Antigen. Cell-surface protein on an infectious agent, cancer cell, or cell of another organism that marks it as foreign. Axon. Long, slender extensions of neurons down which neuronal electrical impulses travel, culminating in the release of neurotransmitter across the synapse to a target cell. B lymphocytes, or B cells. Specialized cells of the immune system, products of hematopoiesis, that release antibodies. Blastomere. One of the cells resulting from division of the fertilized ovum. Cerebral cortex. Multilayered sheet of neurons that covers the cerebral hemispheres of the brain and coordinates and controls many functions including sensation, movement, and cognition. Chorionic villi sampling (CVS). Prenatal testing method in which fetal cells are aspirated from early placenta (villi) and analyzed for genetic abnormalities. Cryopreservation. Preservation of biological tissue by freezing.

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Fetal Research and Applications: A Conference Summary Cystic fibrosis. A genetic disease that affects a number of organ systems, particularly the respiratory, gastrointestinal, and reproductive systems, and leads to early death. Cytochrome P450. Specific type of enzyme involved in the metabolism of foods, drugs, and environmental chemicals. Diploid. Cell containing double pairs of chromosomes in the nucleus. In general, all cells except the gametes (ovum and sperm) are diploid. L-Dopa. A precursor of dopamine used as a treatment for Parkinson's disease. Dopamine. A neurotransmitter. Malfunction of dopamine cells in specific brain regions gives rise to Parkinson's disease. Embryo. Unborn conceptus in early weeks of pregnancy, usually up to the ninth week. Enzymes. Proteins that induce chemical reactions in other molecules. Fetus. Unborn conceptus in later weeks of pregnancy, usually after ninth week. Fluorescence in situ hybridization (FISH). Technique for finding specific regions of DNA in a large mix (or in cells) by using chemically labeled, single strands of complementary nucleotide sequences to serve as probes that are detected by fluorescent compounds. Fragile X syndrome. The most common form of inherited mental retardation. (See X-linked diseases.) Gamete. Reproductive germ cell; a sperm is the male gamete, an oocyte the female gamete.Gamma globulin. A preparation of blood proteins, containing antibodies, that can be administered to boost immune responses. Genome. The entire genetic repertoire of a cell. Graft-versus-host disease. Rejection of the recipient's body cells or tissues by the immune responses of the donor, a particular problem in transplantation of hematopoietic tissue such as bone marrow. Haploid. Cell with a single set of chromosomes, as in sperm and oocytes. HDL. High-density lipoprotein. Lipoproteins are compounds of fats and proteins. In adults, HDL participates in cholesterol metabolism: in the uterus, HDL seems to regulate placental hormones involved in fetal growth. Hematopoiesis. Process though which precursor cells give rise to all the varieties of blood cells. Hematopoietic stem cells. Precursor cells that give rise to different blood cells and to other stem cells. Hippocampus. Area of the brain involved in memory formation.

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Fetal Research and Applications: A Conference Summary HIV. Human immunodeficiency virus, the causative agent of acquired immunodeficiency syndrome (AIDS). Hormones. Blood-borne messenger molecules of the endocrine system that regulate cellular activity in distant organs. Huntington's disease. An inherited, progressive neurological disorder that begins in early middle age and leads to eventual loss of motor and mental function. Hurler's disease. An inherited mucopolysaccharide storage disease, caused by an inborn enzyme deficiency, that causes abnormalities in a variety of organ systems and leads to early death. Hydrops. Severe fetal edema. Immortalized cell. Cell that divides indefinitely because of the introduction of viral, cancer-inducing oncogenes. The cancer-inducing properties are removed. Imprinting. Preferential or exclusive expression of a gene from a paternally or maternally derived chromosome. In vitro. In the test tube or culture dish. In vivo. In a living organism. Islet cells. Also called beta cells. Specialized cells clustered in the pancreas that are responsible for insulin production. Lesch-Nyhan disease. A disease inherited only by males (X-linked) associated with lack of function of a specific enzyme and marked by neurological dysfunction, mental retardation, and self-mutilation. Lymphocyte. White blood cell. Meiosis. Division of a precursor, diploid, germ cell to produce haploid gametes. Mitosis. Division of cells other than germ cells to produce daughter cells. Monoclonal antibody. Antibody engineered for exceptional specificity for targeting antigens. MPTP. A compound that induces severe symptoms of Parkinson's disease. MPTP has been used to create animal models of parkinsonism for research. Myotonic dystrophy. Inherited muscle-wasting disease. Neural tube. Embryonic structure from which the brain develops, it contains the precursor cells that give rise to different classes of neurons. Neuron. Nerve cell. Neurotransmitter. Chemical messenger of communication between neurons and other neurons, or neurons and muscle cells. Nucleotide. Constituent molecule, or subunit, of DNA and RNA. The order of specific nucleotide sequences forms the genetic code for protein production.

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Fetal Research and Applications: A Conference Summary Oncogene. Gene that induces cancerous transformation in a cell. Oocyte. Female gamete. Percutaneous umbilical blood sampling (PUBS). Method of entering the bloodstream of the fetus through the umbilical vein, also called cordocentesis. Peritoneal cavity. Space between the lining of the abdominal cavity and the abdominal organs. Polymerase chain reaction (PCR). Technique whereby millions of copies of a DNA fragment can be generated from a single copy. Primer extension preamplification (PEP). Variation of PCR that allows amplification of whole chromosomes and genomes. Receptors. Cellular molecules that recognize and bind other external molecules including neurotransmitters, hormones, and antigens. Rh disease. Condition brought on by immune system incompatibilities between mother and fetus, based on the presence or absence of a specific protein on blood cells (Rh factor), in which the mother's immune system attacks fetal blood cells. SCID-hu mouse. Mouse strain with severe combined immunodeficiency, into which human cells have been implanted. Sex-linked diseases. See X-linked diseases. Spermatocyte. Precursor stage in development of sperm. Spinobulbar muscular atrophy. Inherited muscle-wasting disease, X-linked. Stem cells. Multipotent precursor cells from which differentiated cells arise. Striatum. Target area of the brain for dopamine-releasing neurons of the substantia nigra. Substantia nigra. Area of the brain containing dopamine-releasing cells that project to another brain area, the striatum. This connection is important in motor control and is damaged in the brains of patients with parkinsonism. T lymphocytes, or T cells. Cells involved in immune system response to antigens and graft rejection. Tay-Sachs disease. An inherited disorder, marked by inability to break down a fatty substance in the brain, resulting in mental and physical degeneration. Tocolytics. Drugs that prevent preterm labor. Transcription. Process by which RNA is synthesized on a DNA template. Transformed cell. Cancer cell. Transgenic animals. Animals, often mice, to whose genome new, functional DNA fragments have been added by transection of fertilized eggs. Ultrasound. Prenatal diagnostic tool that uses sound waves to create moving images of the fetus.

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Fetal Research and Applications: A Conference Summary X and Y chromosomes. Chromosomes that differ in the two sexes. Human females have two X chromosomes (XX) and males have XY. X-linked diseases. Diseases caused by a mutation in a gene on the X chromosome. Females are usually protected by the presence of a normal X, but may transmit the abnormal X to their offspring. In contrast, male children will be affected by the disease if their (single) X chromosome carries the mutation. An example of this type of inherited disorder is hemophilia. Xenograft. Graft of tissue derived from one species implanted into different species. Zona pellucida. Oocyte outer coat.