Notes

Appendix 2. Glossary of Biotechnology Terms

Adult (or somatic) stem cell: A non-scientific term for any undifferentiated multipotent or pluripotent cell not derived from an embryo but found in the human body after the embryonic or foetal stage of development. An adult stem cell can renew itself and differentiate to give rise to all the specialized cell types of the tissue from which it originated. Recent research has found that some adult stem cells have nearly pluripotent properties.

Artificial insemination: The injecting of a sample of specially treated sperm from the male partner, or a third party donor, into the female partner's reproductive tract.

Bioethics: broadly, the branch of philosophy that considers what is and is not ethically acceptable in medical practice and research. More specifically, the normative system of ethics based on utilitarian principles, developed at the behest of a committee of the United States Congress, governing the use of human beings in medical research, end-of-life decisions taken by physicians and now, the use of human embryos and cloning. (See “Principlism” in the Glossary of Philosophical Terms).

Blastocoel: The fluid-filled cavity inside the blastocyst.

Blastocyst: A preimplantation embryo of about 150 cells produced by cell division following fertilization. The blastocyst is a sphere made up of an outer layer of cells (the trophoblast), a fluid-filled cavity (the blastocoel), and a cluster of cells on the interior (the inner cell mass).

Blastomere: a type of cell produced by division of the embryo in the early stages of life. Blastomeres of the inner cell mass of a blastocyst are the “embryonic stem cells” sought by some scientists for their pluripotent characteristics. If the embryo is left undisturbed, these inner blastomeres will divide and differentiate to form all the tissues of the child’s body.

Bone marrow stromal (stem) cell: Also known as mesenchymal stem cells. Cells derived from the non-blood forming fraction of bone marrow. Bone marrow stromal cells are capable of growth and differentiation into a number of different cell types including bone, cartilage and fat.

Blastomere separation: A method of cloning that involves the removal from an early term embryo of one or more totipotent blastomeres

Cadaveric foetal tissue: obtained through medical research supply companies from abortion hospitals or private, stand-alone abortion facilities. Foetal tissue implant or fetal cell therapy is implanting tissue or cells from a foetus into a patient for treatment of disease.

Cell division: Method by which a single cell divides to create two cells. There are two main types of cell division: mitosis and meiosis.

Cell culture: Growth of cells in vitro in an artificial medium for experimental research.

Cell line: Cells that can be maintained and grown in culture and display an immortal or indefinite life span.

Chimera: ( Lat. Chimaera) a monstrous creature of mythology of Asia Minor, which was made of the parts of multiple animals. In biology, a combination of two or more fused embryos (derived from two separate zygotes of the same species, also called “fraternal,”) single individual. It is also possible that two spermatozoa and that fusion then results in a single embryo. See also “Mosaic”.

Cloning: Any asexual means of producing or altering the genetic makeup of a cell or organism. Cloning may occur by propagation of cuttings, as in the case of plants; continual budding, as in the case of hydra; fission, as in the case of bacteria and protozoa; parthenogenic asexual reproduction as in the case of aphids. Somatic cell nuclear transfer is one technique among many to create clones in higher animals. Others, some occurring naturally, include twinning by separation of blastomeres, mitochondrial transfer and pronuclear transfer.

Cryopreservation: is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures. Typically the procedure involves the use of liquid nitrogen. At such low temperatures, any biological activity is effectively stopped.

Differentiation: The process by which a cell acquires the characteristics and specialized function of a particular tissue type.

Diploid cell: Diploid cells have two homologous copies of each chromosome, usually one from the mother and one from the father. In human embryos the number is normally 46. Nearly all mammals are diploid organisms.

Directed differentiation: Manipulating stem cell culture conditions to induce differentiation into a particular cell type.

DNA: Deoxyribonucleic acid, a chemical found primarily in the nucleus of cells. DNA carries the instructions or blueprint for making all the structures and materials the body needs to function.

Ectoderm: Outermost germ layer of cells derived from the inner cell mass of the blastocyst; gives rise to the nervous system, sensory organs, skin, and related structures.

Embryo: The child is called an embryo from the moment of fertilization until the end of the 8th week of gestational age, whereafter it is instead called a foetus.

Embryoid bodies: Rounded collections of cells that arise when embryonic stem cells are cultured in suspension. Embryoid bodies contain cell types derived from all 3 germ layers.

Embryonic germ cells: Pluripotent stem cells that are derived from early germ cells (those that would become sperm and eggs). Embryonic germ cells (EG cells) are thought to have properties similar to embryonic stem cells.

Embryonic stem cells: a non-scientific term referring to the cells taken from the inner cell mass of an early-term embryo or blastocyst. These are the “pluripotent” and “totipotent” cells sought by researchers for their potential to form every tissue in the human body.

Embryonic stem cell line: Embryonic stem cells that have been cultured under in vitro conditions that proliferate without differentiation for months to years.

Endoderm: Innermost layer of the cells derived from the inner cell mass of the blastocyst; it gives rise to lungs, other respiratory structures, and digestive organs, or generally "the gut".

Eugenics: a social philosophy which advocates the improvement of human hereditary traits through various forms of intervention. The goals of various groups advocating eugenics have been to create healthier, more intelligent people, to save society's resources, and lessen human suffering. Modern proposed means of achieving these goals always involve aborting unfit children and sterilization of fertile women and men. With the development of NRT’s the tools used include prenatal testing and screening, genetic counseling, birth control, in vitro fertilization, and genetic engineering. Eugenics derives from utilitarian philosophies and formed the foundation of the Nazis’ “racial hygiene” programs in which millions of disabled, elderly, poor, or racially “undesirable” persons were killed.

Fertilization: The joining of the male and female gametes.

“Fertilized egg”: a misnomer commonly found in the media reports on embryo research. The term is generally used as a euphemism to avoid the controversy over embryonic stem cell research and cloning. Most mammals do not have “eggs” but the term is used to avoid using the more politically charged word “embryo”.

Foetal reduction: or “selective reduction”. The aborting of one or more children in cases of multiple pregnancy. Multiple pregnancy frequently follows the use of fertility enhancing drugs.

Foetus: from Latin, literally, “offspring”. It refers to a stage of the child’s development in the uterus after about eight weeks up to birth; before eight weeks, the child is usually referred to as an embryo.

Gametes: mature male (sperm) or female (ova) sex cells.

Gene: A functional unit of heredity that is a segment of DNA found on chromosomes in the nucleus of a cell. Genes direct the formation of an enzyme or other protein.

Germ line cells: those cells formed at a very early embryonic stage that form the gametes, or sex cells of the individual. These diploid cells begin to form in the early embryo as early as 2 – 2 ½ weeks post-fertilization or after cloning; after years of maturing, they form the haploid sex gametes (sperm and oocytes germline cells are not somatic cells). Genetic changes to these cells are passed down to the next generation when the individual reproduces. One of the many techniques of cloning being pursued by researchers is Germ Line Cell Nuclear Transfer as distinct from Somatic Cell Nuclear Transfer.

Germ layers: The three layers of an embryo that will later form the different parts of the body. The three layers are the ectoderm, the mesoderm, and the endoderm.

Germ Line Gene Transfer: The injection of “foreign” DNA or genes into cells or embryos – “gene transfer” – can be used for “enhancement” or for “corrective” purposes. This is a form of eugenics, the effort to “improve” the human race by eliminating unwanted characteristics. In the case of DNA Recombinant Germ Line Gene Transfer, it is the direct manipulation of the genetic make-up of successive generations of human beings.

Haploid cell: a cell containing only half the normal number of chromosomes of an individual of a given species, as in mature gametes. In the case of humans, each sex cell at the point when it is ready to fuse normally has 23 chromosomes.

Heterologous IVF: the technique used to obtain a human conception through the meeting in vitro of gametes taken from at least one donor other than the two spouses.

Homologous IVF: the technique used to obtain a human conception through the meeting of gametes of both the spouses.

Human cloning: (a) organism: the duplication, or near-duplication, of a whole human being using any cloning technique; or, the use of part(s) of human cellular or artificial materials for the purpose of duplicating a whole human being using any technique; (b) molecules: permanently altering the human genome in successive reproductive generations by means of the duplication, or near duplication, of human genetic materials using any a-sexual reproductive technique and/or any sexual reproductive technique.

Human genome: The total nuclear and cytoplasmic DNA genetic materials that constitute an organism as an individual member of the human species.

Inner cell mass: The cluster of cells inside the blastocyst. These cells give rise to the embryo and ultimately the fetus. The inner cell mass cells are used to generate embryonic stem cells. See also “blastomere.”

Intracytoplasmic sperm injection: Injection of a single sperm into a selected ovum. It is most commonly used to overcome male infertility problems. It is one of the artificial procreation techniques most frequently cited in studies on the incidence of birth defects in the new reproductive technologies.

In vitro: Latin for "in glass"; in a laboratory dish or test tube; an artificial environment.

In vitro fertilization: A procedure where an oocyte and sperm cells are brought together in a dish (i.e. in vitro). The resulting zygote, will start dividing and after a several divisions, can be implanted into the womb of a woman.

Meiosis: Cell division of a gamete to reduce the chromosomes within it to half the normal number. This is to ensure that fertilization restores the full number of chromosomes rather than causing aneuploidy, or an abnormal number of chromosomes.

Mesenchymal stem cells: See “bone marrow stromal (stem) cell”.

Mesoderm: Middle germ layer cells of an embryo. It gives rise to bone, muscle, connective tissue, kidneys, and related structures.

Mitochondria: a membrane-enclosed organelle, found in most eukaryotic cells. Mitochondria are sometimes described as "cellular power plants," because they generate most of the cell's supply of ATP, used as a source of chemical energy. Mitochondrial DNA remains in the ennucleated oocyte and in the embryo resulting from the SCNT process.

Mitochondrial transfer cloning: an a-sexual form of manipulation of an embryo (cloning) in which the mitochondria (containing mitochondrial DNA) from a human donor female oocyte are transferred to another human female oocyte, or to a newly produced human embryo.

Mitosis: The division of the nucleus of any cell with a full complement of chromosomes, separating the duplicated genome into two sets identical to the parent's. Stem cells replicate by mitosis.

Mosaic: or mosaicism, in one individual, denotes the presence of two populations of cells with different genotypes, developed from a single embryo. Mosaicism may result from a mutation during development which is propagated to only a subset of the adult cells. Although the two can have some common symptoms, mosaicism is distinct from chimerism. In the latter, the two or more genotypes arise from more than one zygote, while in mosaics, these genotypes arise from only a single cell.

Multipotent: Stem cells that can form many differentiated cell types, but all within a particular tissue, organ, or physiological system. Blood-forming (hematopoietic) stem cells are single multipotent cells that can produce all cell types that are normal components of the blood.

Neural stem cell: A stem cell found in adult neural tissue that can give rise to neurons and glial (supporting) cells.

NRT: New Reproductive Technologies. any artificial intervention employed to obtain a living human being at any stage of development for “reproductive” purposes. That is, any method of making a human being in the embryonic stage of life by any means other than sexual intercourse.

Cloning is included in these because a human being is created and is fully in existence from the first moment of the proper ordering of the genetic material that makes up the human being at the earliest stage of life whether that ordering has been brought about by the combination of oocytes and sperm or by any other non-sexual method.

Organ farming: (Theoretical). Scientists have proposed that one use of therapeutic cloning, that is, the creation of a live cloned human being to be used as a source of stem cells or research material, could be the creation of human bodies, kept alive through artificial means, that could yield genetically matched replacement organs for patients. In theory, these bodies could be created by cloning from the genetic material of the patient and thereby avoid the problem of immune system tissue rejection common to conventional organ replacement.

Parthenogenesis: A form of reproduction where an embryo develops without the fusion of sperm with the oocyte. Parthenogenesis occurs naturally in some species, including lower plants, invertebrates (e.g. water fleas, aphids, some bees and parasitic wasps), and vertebrates (e.g. some reptiles, fish, and, very rarely, birds and sharks). Some scientists have proposed artificially inducing parthenogenesis with human oocytes as a means to obtain stem cells without fertilization. It is sometimes also used to describe reproduction modes in hermaphroditic species which can self-fertilize.

Peripheral blood stem cell transplantation: a method of replacing blood-forming cells destroyed by cancer treatment. Stem cells found in the circulating blood, similar to those in the bone marrow, are given to the patient after treatment. Transplantation may be autologous (an individual's own blood cells saved earlier), allogeneic (blood cells donated by someone else), or syngeneic (blood cells donated by an identical twin). Also called peripheral stem cell support.

Preimplantation genetic diagnosis: A eugenic practice commonly offered by IVF facilities. It involves the removal of one or more blastomeres from an early term embryo and examination for genetic abnormalities. The undesired embryos are usually either discarded or donated for research. It is commonly used to “screen” for possible indications of Down’s syndrome.

Prenatal diagnosis: Using ultrasound or the more invasive and dangerous amniocentesis and choriocentesis, it is the diagnosis of a disease or condition in a foetus or embryo before it is born. The aim is to detect birth defects such as neural tube defects, chromosome abnormalities, genetic diseases and other conditions. It can also be used to determine the sex of the unborn baby. A child seen to have a disorder is sometimes treated in utero but very frequently aborted.

Diagnostic prenatal testing can be by invasive methods or non-invasive methods. An invasive method is when probes or needles are inserted into the placenta, e.g. amniocentesis, which can be done from about 14 weeks gestation, and sometimes results in a miscarriage. Chorionic villus sampling can be done earlier (between 9.5 and 12.5 weeks gestation) but is slightly more risky to the unborn child. Non-invasive methods such as ultrasound and maternal serum screens

can evaluate risk of a condition but not determine 100% if the child has a condition.

Principlism: an academic theory of ethics which was formally articulated for the first time in 1978 by the Congressionally-mandated National Commission in their Belmont Report. That report identified three bioethics principles: “respect for persons” (autonomy), justice and beneficence. These have consistently been given strict utilitarian interpretations since their implementation in most medical and research institutions.

Plasticity: The ability of stem cells to generate the various differentiated cell types.

Pluripotent: Ability of a single stem cell to give rise to all of the various cell types that make up the body. Pluripotent cells cannot make so-called "extra-embryonic" tissues such as the amnion, chorion, and other components of the placenta.

Polar Body: a molecule ejected by the oocyte at the time of fertilization containing 23 female chromosomes. Polar bodies can be recovered and the genes used in some cloning processes.

Progenitor cell: often confused with stem cells, progenitor cells differ in that they can only differentiate. They cannot renew itself indefinitely through cell division. Progenitor cells are usually limited in the kinds of cells it can become than a stem cell. Pogenitor cells are found in the various tissues of the body. Their main role is to replace cells lost by normal attrition.

Pronuclear transfer cloning: a form of a-sexual reproduction (cloning) in which male and/or female pronuclei are transferred from one or more embryos to an enucleated oocyte to create an embryo.

Pronucleus: The haploid nucleus of a sperm or oocyte after fertilization but before fusion of the nuclei.

“Reproductive cloning”: Creating a cloned organism for the purpose of reproduction, either in animals or humans. The term is commonly used in the media and by researchers to create a false distinction between “therapeutic” and “reproductive” cloning to gain public and political support. Public opinion is largely against the creation of cloned human children but when the term “therapeutic cloning” is used, the reaction is largely favourable, even though the process is precisely the same except that the cloned person is killed and used to obtain stem cells.

Sex selection: the selection of embryos created in the lab for a particular sex. The practice is outlawed in some countries but is still widely practiced and usually involves the elimination of girls.

Somatic cell nuclear transfer (SCNT): A method of cloning in which the nucleus of a female gamete is removed and replaced with the nucleus of a somatic (body) cell of another organism. to make an embryo. SCNT is often taken as synonymous with cloning, but in reality it is only one method of creating a clone among many.

Somatic stem cells: See “adult stem cells”.

Stem cell: a general term, (now falling into disuse in scientific literature) that refers to any undifferentiated cell having the ability both to self-replicate by cell division and differentiate into one or more types of tissue in the body.

Surrogacy: an arrangement whereby a woman agrees to become pregnant for the purpose of gestating and giving birth to a child for others to raise. She may be the child's genetic mother (the more traditional form of surrogacy), or she may be implanted with someone else's IVF embryo (gestational surrogacy).

“Therapeutic cloning”: The use of any method of cloning to obtain a living embryo in order to use that embryo’s cells for research or therapeutic application. Often used in media and by researchers to create a false distinction between two “types” of cloning “reproductive” and “therapeutic.” In reality the two terms refer only to the intended use of the cloned embryo. See “reproductive cloning”.

Totipotent: (From Latin) literally “having all powers”. Stem cells that can give rise to all cell types that are found in an embryo, foetus, or developed organism, including the embryonic components of the trophoblast and placenta required to support development and birth. The zygote and the cells at the very early stages following fertilization (i.e., the 2-cell stage) are considered totipotent.

Trophoblast: The extraembryonic tissue responsible for implantation, developing into the placenta, and controlling the exchange of oxygen and metabolites between mother and embryo.

Twinning: in NRT procedures, means the creation of identical twins by the separation of one or more totipotent blastomeres from the early term embryo.

Umbilical cord stem cells: Blood-derived (Hematopoietic) stem cells present in the blood of the umbilical cord during and shortly after delivery. Umbilical cord stem cells are similar to stem cells that reside in bone marrow, and have been found to have embryo-like qualities in recent research. Efforts are now being undertaken to collect these cells and store them in freezers for later use.

Undifferentiated: A cell that has not yet generated structures or manufactured proteins characteristic of a specialized cell type.

Zygote: An embryo at the earliest single-cell stage after fertilization. Two haploid sex cells, an ovum from a female and a sperm cell from a male, merge into a single diploid cell called the zygote.