Animal & Veterinary

Animal Cloning Risk Assessment Glossary

The following terms are defined as they are used within the current risk assessment. Unless otherwise indicated, definitions provided are the commonly accepted use of the term(s) at the Center for Veterinary Medicine, and may have been derived from various 115 sources.

alleleAny alternative form of a gene that can occupy a particular chromosomal locus.
anal atresiaAbnormally closed anal opening.
analyteA substance undergoing analysis.
aneuploidDescribes a cell or organism which has an abnormal total number of chromosomes and where numbers of individual chromosomes are out of proportion with the numbers of the other chromosomes. Too many chromosomes is called hyperploidy; too few is called hypoploidy.
animal clonesAnimals derived via somatic cell nuclear transfer techniques. The terminology employed in this assessment did not use “cloned animals.” The phrase “cloned animals” does not clearly differentiate between the animal serving as the source of genome being propagated, or the animal that has been generated from a particular source. For example, the sentence “That field contains several cloned animals” does not specify whether the animals had been used as a source of material for SCNT or whether they had been generated by that technology.
ARTsAssisted reproductive technologies.
biallelicReferring to expression of two alleles at the same time.
bioengineered animalsThe broadest category of animals associated with molecular biology techniques, including animal clones and all genetically engineered animals.
blastocystAn early stage in the development of mammalian embryos, when the embryo is a spherical body comprising an inner cell mass that will become the fetus and an outer ring of cells, the trophectoderm, that will become part of the placenta.
blastomereAny one of the cells formed from the first few cell divisions in animal embryology. The embryo usually divides into two, then four, then eight blastomeres, and so on.
Blastomere Nuclear Transfer ( BNT)An assisted reproductive technique in which a blastomere is used as a donor for nuclear transfer into enucleated oöplasts.
capacitationThe process of sperm maturation (or activation) that occurs post-ejaculation. Allows the spermatozoa to go through the acrosomal reaction in which factors in the sperm head that allow it to penetrate the egg are released and fertilize an oöcyte.
caruncleThe site of attachment in the maternal uterus of the ruminant for the placental cotyledon (see cotyledon).
centromere (centromeric)A specialized chromosome region to which spindle fibers attach during cell division (mitosis) that is genetically inactive. This is constricted region of a mitotic chromosome that holds sister chromatids together—the crossing point in the “X” often used to depict chromosomes.
chimeraAn organism or recombinant DNA molecule created by joining DNA fragments from two or more different organisms.
chondrocyteA mature cartilage cell.
chorionThe outermost membrane enclosing the fetus. It is formed from tissues on the outside of the embryo such as the trophoblast, and the part of it attached to the uterus wall eventually develops into the placenta.
chromatidOne of the two daughter strands of a duplicated chromosome.
chromatinThe network of fibers of DNA and protein that make up the chromosomes of the eukaryotic nucleus during interphase.
chromosome(s)A structure composed of one very long molecule of DNA and associated proteins (e.g. histones) that carries hereditary information.
cleavageThe series of mitotic divisions by which a fertilized animal ovum changes, without any overall change in size, into a ball of smaller cells constituting the primitive embryo.
cloneA group of cells or individuals that are genetically identical as a result of asexual reproduction including nuclear transfer.
cloningAsexual reproduction of animals using somatic cell nuclear transfer (SCNT).
coherenceThe extent to which a hypothesized causal association is compatible with preexisting theory and knowledge.
colostrumThe first fluid secreted by the mammary glands at the time of birthing that is rich in antibodies and nutrients, and precedes the production of true milk. Its ingestion confers passive maternal immunity on the offspring of some species.
Comprehensive Veterinary Exam (CVE)Systematic approach for examining domestic livestock animals and making informed judgments as to their health. The CVE contains both objective and subjective information and is performed by a veterinarian.
congenitalExisting at, and usually before, birth; referring to conditions that are present at birth, regardless of their causation.
consistency Close conformity between findings in different studies conducted by different methods or different investigators.
cortisolThe major natural glucocorticoid hormone synthesized in the zona fasciculata of the adrenal cortex; it affects the metabolism of glucose, protein, and fats. It also regulates the immune system and affects many other functions.
cotyledonA lobule structure in ruminant placentae that form contact points between the fetal-derived placental tissues with the maternal caruncles (attachment points) of the uterus to form the functional units called placentomes. It consists mainly of a rounded mass of villi.
cryptorchidA male animal with one or both testicles retained within the body cavity.
cullTo remove unwanted members or parts from a herd.
cytoplasmThe living contents of the cell, exclusive of the nucleus, consisting of an aqueous protein matrix or gel, and where essential membranes and cellular organelles (mitochondria, plastids, etc.) reside.
de novo Literally means “anew.” Beginning a process from its origin with out prior plans.
dermatitis vegetansA hereditary disease of the skin in swine (see hyperkeratosis).
differentiationThe process whereby relatively unspecialized cells, e.g. embryonic or regenerative cells, acquire specialized structural and/or functional features that characterize the cells, tissues, or organs of the mature organism or some other relatively stable phase of the organism’s life history.
diploidHaving two sets of chromosomes.
DNAAbbreviation for deoxyribonucleic acid; one of the two types of nucleic acids that constitutes the genetic material of most known organisms; usually in double helix form .
DNA polymeraseThe enzyme responsible for copying DNA. Common name for either of two categories of enzymes that catalyze the synthesis of DNA from deoxyribonucleoside triphosphates in the presence of a nucleic-acid primer.
ductus arteriosusThe blood vessel between the pulmonary artery (carries blood from the heart to the lungs for oxygenation) and the aorta (carries oxygenated blood to the rest of the body). During gestation the ductus arteriosus bypasses the fetal lungs, and is normally sealed after birth.
ductus venosusThe blood vessel between the umbilical vein and the caudal vena cava (carries oxygenated blood from the dam, bypassing the liver, through the vena cava to the heart of the fetus). It is normally sealed shortly after birth.
dysregulateAbnormal or impaired control of gene expression.
dystociaAbnormal or difficult labor.
ectodermThe outermost layer of tissue in a developing embryo that will eventually become the skin and/or other outer surface of the organism, the outermost parts of the nervous system, and various other outer and external organs depending on the organism.
embryoIn mammals, the term is restricted to the structure present in the early part of gestation that develops into a fetus.
embryo cloningAnother term for blastomere nuclear transfer.
empiricalThat which can be seen or observed alone, often without reliance on theory.
endodermThe innermost layer of tissue in a developing animal embryo that will eventually become the digestive tract, respiratory tract, and various other things depending on the organism.
enucleateRemoval of an organ or mass from its supporting tissues.
epigeneticDescribing any of the mechanisms regulating the expression and interaction of genes, particularly during the development process. These include changes that influence the phenotype but have arisen as a result of mechanisms such as inherited patterns of DNA methylation rather than differences in gene sequence: imprinting is an example of this.
epigenetic reprogrammingIn the case of somatic cell nuclear transfer (SCNT), the process of altering the instructions governing the expression of genes in the chromosomal DNA of the donor cell such that embryonic or totipotent ( able to differentiate along any line or into any type of cell) gene expression conditions are reestablished.
epigenetic variation/effectsNon-hereditary, phenotypic changes in the expression in a single gene.
estrousPertaining to estrus. (Adjective)
estrusThe recurrent, restricted period of sexual receptivity in female mammals other than human females, marked by intense sexual urge. (Noun)
euchromatinOne of two types of chromatin seen during interphase of the cell cycle. It is genetically active (transcription occurs in it) and less condensed than heterochromatin (the other type of chromatin).
eukaryoteAn organism whose cells have a true nucleus, i.e., one bounded by a nuclear membrane, within which lie the chromosomes, combined with proteins and exhibiting mitosis; eukaryotic cells also contain many membrane-bound compartments (organelles) in which cellular functions are performed.
F 1Abbreviation for filial generation 1 (first generation). The initial hybrid generation resulting from a cross between two parents.
farrowIn swine, the process of giving birth. Also used to describe a litter of pigs.
fat cow syndromeA multifactorial disease condition often occurring in dairy cows following parturition; associated with excessive mobilization of fat to the liver in well-conditioned cows. This mobilization is induced by the negative energy balance and hormonal changes. Presenting signs usually include depression, anorexia, weight loss, and weakness that can lead to recumbency.
fecundityThe physiological ability to reproduce, as opposed to fertility.
fertilityThe capacity to conceive or induce conception.
foramen ovaleA hole in the fetal heart between the right and left atria, for the purpose of bypassing the lungs. It is normally sealed shortly after birth.
founder animalAn organism that serves as the progenitor of a particular lineage.
freemartinA sexually maldeveloped female calf born as a twin to a normal male calf. The reproductive tract hypoplasia results in an infantile uterus that does not develop appropriately with the growth of the rest of the calf and fails to respond to puberty. It is commonly sterile and intersexual as the result of male hormones reaching it through shared placental blood vessels.
gameteA mature reproductive cell capable of fusing with a cell of similar origin but of opposite sex to form a zygote from which a new organism can develop. Gametes normally have haploid chromosome content. In animals, a gamete is a sperm or egg.
gametogenesisThe process of the formation of gametes.
gene expressionThe process by which a cell transcribes the information stored in its genome to carry out the functions of life.
genetic reprogrammingThe process of rearranging the genome of the nucleus to restore a cell’s totipotency so it can differentiate into different types of cells and develop into a whole organism. Also known as de-differentiation.
genetically engineered animalsA subset of animals associated with molecular biology techniques. Includes transgenic animals, animals subjected to gene therapy and mosaic animals. This subset does not include animal clones.
genomeThe full set of genes in an individual, either haploid (the set derived from one parent) or diploid (the set derived from both parents).
genotypeThe entire genetic constitution of an individual.
germ cellA reproductive cell such as a spermatocyte or an oöcyte, or a cell that will develop into a reproductive cell.
giltA female pig that is intended for breeding but has not yet given birth.
gonadotropinAny hormone that stimulates the testes or ovaries.
haploidAn individual or cell having only one member of each pair of homologous chromosomes.
harmAn adverse outcome.
hazardSomething that can produce harm.
heiferA female bovine that has not yet produced a calf.
hematologyThe branch of medicine that deals with the blood and blood-forming tissues.
hemogramA written record or graphic representation of a detailed blood assessment such as the complete blood count or differential leukocyte count.
hermaphroditeAn individual characterized by the presence of both male and female sex organs. The condition is caused by an anomalous differentiation of the gonads: an animal with ambiguous genitalia, typically a penis with ovaries or a vulva with testicles
heterochromatinThe condensed and genetically inactivated portion of a chromosome.
histonesChromatin proteins commonly associated with the DNA of somatic cells in eukaryotes and they are involved in packaging of the DNA and the regulation of gene activity.
hormoneA chemical substance produced in the body by an organ, cells of an organ, or scattered cells, having a specific regulatory effect on the activity of an organ or organs. The term was originally applied to substances secreted by endocrine glands and transported in the bloodstream to distant target organs, but later it was applied to various substances having similar actions but not produced by special glands.
hydroallantoisA bnormal fluid accumulation in the allantoic cavity of the placenta. (See hydrops.)
hydropsEdema. H ydrops refers to a set of conditions relating to abnormal fluid accumulation in one or more compartments of the placenta and/or the fetus itself, and are alternatively referred to as hydroallantois, hydramnios or hydrops fetalis, depending on where the edema occurs.
hyperkeratosisCharacterized by lesions of the superficial layers of the epidermis. These lesions rapidly become covered with scales, and then develop hard, dry crusts with deep fissures. Generally referred to as parakeratosis in swine.
hypoplasiaIncomplete development or underdevelopment of an organ or tissue.
hypospadiusA developmental anomaly in which the urethra opens inferior (below) to its usual location; usually seen in males with the opening on the underside of the penis or on the perineum.
imprinted genesThose genes whose degree of expression is determined by their derivation from either the dam or the sire.
in vitroOutside the organism, or in an artificial environment. This term applies, for example, to cells, tissues or organs cultured in glass or plastic containers.
in vivo Literally means "in life;” a biologic or biochemical process occurring within a living organism.
inner cell massThe group of cells in a blastocyst that are destined to form the fetus.
inner cell mass ( ICM)A cluster of cells within the blastocyst. The inner cell mass will form all of the tissues of the organism and these cells are pluripotent.
ketonuriaKetone bodies in the urine, as in diabetes mellitus; called also acetonuria and hyperketonuria.
ketosisA metabolic disease of lactating dairy cows characterized by weight loss, decreased milk production, and neurologic abnormalities that usually occur during the first 6 weeks of lactation.
Large Offspring Syndrome (LOS)A morphologic syndrome presumably expressed at the molecular and physiological level due to some alterations in embryonic gene expression. Animal clones with LOS may experience difficulties in developing and maintaining the placenta. An LOS fetus is unusually large for its species, has longer than usual gestation periods, and often has immature lungs or heart abnormalities. Kidneys and liver may also be affected.
leukocytosisA transient increase in the number of leukocytes (white blood cells) in the blood.
leukopeniaA reduction in the number of leukocytes in the blood.
locusThe specific site of a gene on a chromosome.
long terminal repeatsA double-stranded sequence, generally several hundred base pairs long, at the two ends of the genetic sequence of retroviruses.
mastitisInflammation of the mammary gland or breast.
meconiumFirst stool in the intestine of a full-term fetus.
meiosisThe process in which a single diploid cell becomes four haploid cells in two consecutive divisions of the nucleus of an eukaryotic cell. In multicellular higher organisms this occurs only in the progenitors of sex cells and never in somatic cells.
methylationThe addition of a methyl group (-CH 3) to a larger molecule (e.g. cytosine methylation) cytosine 5-methyl cytosine
metritisInflammation of the uterus.
mitosisThe division of a eukaryotic cell nucleus to produce two daughter nuclei that contain identical numbers of chromosomes and that are identical genetically to the parent nucleus except where crossing over or mutation has occurred.
monozygotic twinOne of a pair of twins derived from a single fertilized egg or zygote. Synonym: identical twin.
morphologyThe form and structure of an organism, organ, or part.
morulaThe solid mass of blastomeres formed from the cleavage of a fertilized ovum or egg.
murinePertaining to or affecting mice or rats.
neoplasiaAbnormal and uncontrolled cell growth that often produces a tumor (a neoplasm) that may or may not be cancerous (i.e., capable of spread or metastasis).
nuclear transferTransferring the nucleus with its chromosomal DNA from one (donor) cell to another (recipient) cell.
nucleic acidsA large molecule composed of nucleotide subunits. DNA ( deoxyribonucleic acid) and RNA ( ribonucleic acid) are examples.
nucleosideA molecule composed of a purine or pyrimidine nitrogenous base attached to the five-carbon sugar. This glycosylamine is a component of nucleic acids.
nucleotideA molecule composed of a purine or pyrimidine nitrogenous base attached to the five-carbon sugar which also has a phosphate group attached to it. It is the c onstitutional unit into which nucleic acids are broken down by partial hydrolysis and from which they are built.
nucleusThe most conspicuous organelle of a eukaryotic cell; it contains the chromosomes and is the site of genomic DNA replication and or RNA synthesis in the cell.
oöcyteA cell of an animal ovary that undergoes meiosis to form an ovum.
oö plasmic remodelingAfter nuclear transfer, the cytoplasm of the oöcyte ( oöplasm) alters the morphology of the nucleus, so that it more closely resembles the nucleus of an embryo.
oö plastThe remaining portion of the oöcyte following enucleation.
oviductA tube from the ovary to the uterus through which ova (eggs) may pass.
ovumThe female reproductive cell which, after fertilization, becomes a zygote that develops into a new member of the same species. Also called an egg.
parakeratosisA nutritional deficiency disease of 6- to 16-wk-old pigs that is characterized by lesions of the superficial layers of the epidermis. It is a metabolic disturbance resulting from a deficiency of zinc or an excess of calcium in the diet.
parityThe condition of having given birth.
parthenogenesisThe development of a new individual from an unfertilized female gamete.
parturitionThe act or process of giving birth to offspring.
patent ductus arteriosusThe failure of the ductus arteriosus to close after birth resulting in extra blood flow to the lungs and recirculation of oxygenated blood to the lungs rather than the rest of the body.
patent urachusThe failure or the urachus to close during parturition, resulting in the inability to excrete urinary waste.
phagocytosisThe uptake of extracullular materials by the formation of a pocket from the cellular membrane and its subsequent pinching off.
phenotypeThe totality of the observable functional and structural characteristics of an organism as determined by its genotype and its interaction with its environment.
phytate(s)A form of phosphorus commonly occurring in grain products, which is indigestible in non-ruminant species.
placentomesPlacental junctures consisting of the uterine caruncle and the placental cotyledon, which permits vascular transport of nutrients into and waste out of the fetal environment.
ploidyDegree of repetition of the basic number of chromosomes.
pluripotentCapable of differentiating into more than one cell type.
polar bodyA small cell containing little cytoplasm that is the by-product of o ö cyte meiosis in female animals.
polycythemiaAn increase in the total red cell mass of the blood.
polymorphismDescribes a substance that can take on several different forms. Can refer to subtle differences in DNA sequences among individuals. It also may refer to a protein which can be coded by several different sequences; these variations do not ruin the protein's function.
polyploidyThe state of a cell having more than two times the haploid number of chromosomes in its nucleus.
portalAnatomical nomenclature pertaining to an opening, especially the site of entrance to an organ of the blood vessels and other structures supplying or draining it.
predationThe capturing and consumption of prey as a means of maintaining life.
pregnancy toxemiaA pathologic metabolic disturbance of pregnancy that results when fetal carbohydrate or energy demand exceeds the maternal supply during the last trimester of pregnancy. Specific to sheep and goats.
preimplantationA period very early in embryo development, before the embryo attaches to the uterus.
progenyAn animal derived from sexual reproduction that has at least one cloned animal as a parent (but could result from two cloned animals mating).
promoterA sequence of the DNA molecule to which RNA polymerase will bind and initiate transcription.
promoterA segment of DNA acting as a controlling element in the expression of a gene.
promoter-enhancer sequenceA control element that can increase expression of a gene.
pronucleusThe pronucleus is the structure that contains the haploid genome of the sperm or ovum after fertilization occurs, but before they fuse to make the nucleus of the zygote, or the single-celled diploid organism.
p-valueA measure of the probability that a difference between groups during an experiment happened by chance.
recumbancyLying down.
renderingReducing, converting, or melting down animal by-products by heating; a cooking and drying process that yields fat of varying grades, both edible and inedible (depending on raw material source), and animal protein that is useful for animal feeds and fertilizer.
riskA set of conditions that links an exposure to the likelihood of an adverse outcome.
risk assessmentThe methodology used to characterize potential risks and the conditions that result in the potential to experience risk.
risk managementThe set of activities applied to identify and evaluate alternative strategies (often regulatory), and select among them on the basis of economic, political, scientific, ethical and social conditions or criteria.
RNAAbbreviation for ribonucleic acid that serves to carry information from DNA to other parts of the cell or that has other functions. The generation of messenger RNA is a critical step in gene expression.
RNA polymeraseAn enzyme that transcribes the information in a DNA sequence into RNA.
ruminantAnimals having a rumen - a large digestive sac in which fibrous plant material is fermented by commensal microbes, prior to its digestion in a "true" stomach (the abomasum). Common farm ruminants are cattle and sheep.
SCNTAcronym for Somatic Cell Nuclear Transfer. The process of generating a live organism asexually by transferring the diploid nucleus of a somatic cell from a donor animal to the enucleated embryo of a recipient animal.
scoursSevere diarrhea in farm animals.
senescenceThe process or condition of growing old in which cells, tissues, and organisms deteriorate and finally die.
sequellaeMorbid conditions occurring as a consequence of another condition or event.
sexual reproductionThe production of offspring by the fusion of male and female gametes (in contrast to ‘asexual reproduction’).
somatic cellAny cell of an organism other than a germ cell.
stem cellA totipotent or pluripotent cell that can replicate indefinitely and which can differentiate into other cells; stem cells serve as a continuous source of new cells.
stochasticPertaining to a random process, used particularly to refer to a time series of random variables. Arrived at by skillful conjecture; e.g. a stochastic model, a stochastic process.
superovulateTo produce numerous ova at one time.
telomeraseA DNA polymerase enzyme that maintains the structure of the telomere by adding the required repetitive sequences to the ends of eukaryotic chromosomes.
telomereThe structure that seals the end of a chromosome.
tetraploidAn organism or cell containing four haploid sets of chromosomes (see polyploidy).
totipotentCapable of becoming any cell type in the body.
transcriptionThe process by which a single-stranded RNA with a base sequence complementary to one strand of a double-stranded DNA is synthesized.
transgenicContains heritable DNA from another source. A transgenic animal is one that has been intentionally altered using molecular biology techniques that result in heritable changes (insertions, deletions or rearrangements) in the nucleic acid sequence of the nucleus or mitochondria, and includes any offspring that inherit those changes.
translationThe second major step of gene expression in which the particular sequence of bases in the transcribed mRNA determines the sequence of amino acids in the proteins (or polypeptides) being synthesized (see transcription).
transposable elementA genetic element that has the ability to move (transpose) from one site on a chromosome to another.
trophectodermThe group of cells in the blastocyst that form the placenta and other non-fetal tissues.
trophoblastA layer of extra-embryonic ectodermal tissue on the outside of the blastocyst. It attaches the blastocyst to the endometrium of the uterine wall and supplies nutrition to the embryo.
urachusA structure through which a fetus excretes urinary waste. In normal development, this structure would close at the time of parturition.
ventricle (ventriculus)A small cavity or chamber within a body or organ, especially: (a) the chamber on the left side of the heart that receives oxygenated arterial blood from the left atrium and contracts to force it into the aorta; and (b) the chamber on the right side of the heart that receives deoxygenated venous blood from the right atrium and forces it into the pulmonary artery.
villiMicroscopic vascular protrusions from the surface of a membrane.
wild typeThe phenotype that is characteristic of most of the members of a species occurring naturally and contrasting with the phenotype of a mutant.
xistEnzyme that deactivates one of the two X chromosomes in female embryos.
zona pellucidaThe thick, transparent, non-cellular outer layer surrounding an o öcyte and fertilized ovum.
zygoteThe diploid cell that results from the union of a sperm cell and an egg cell.

 115  The various sources used for these definitions include:  Dorland’s Medical Dictionary, 30th Ed., W.B. Saunders Company, Philadelphia, 2003; Dictionary of Epidemiology. 3rd Ed. John M. Last. Oxford University Press, 1995; HTTP://;; Large Animal Internal Medicine, 2nd Ed., Smith, B.P., Ed., Mosby – Year Book, Inc., St. Louis, 1996.; Veterinary Medicine: A Textbook of the Diseases of Cattle, Sheep, Pigs, Goats and Horses. 7th Ed. Blood, D. C. and O. M. Radostits, Philadelphia: Bailliere Tindall Company, 1989. The Merck Veterinary Manual, 8th Ed. Online Version.  C.M. Kanh and S Line, Ed. Merck & Co., Inc, NJ, 2003; and The American Heritage® Dictionary of the English Language, 4th Ed., Houghton Mifflin Company. 2002.

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