Select Committee on Science and Technology Fifth Report


Blastocyst  The preimplantation embryo of mammals consisting of a sphere of cells with an outer cell layer that forms the placenta (trophectoderm) and a cluster of cells on the interior called the inner cell mass that forms the embryo and from which embryonic stem cells may be derived

Cell nuclear replacement (CNR)  The process whereby a nucleus (which contains almost all the DNA of the human/animal in question) is placed in an egg in which the nucleus has been removed. This process of cell nuclear replacement led to the birth of the sheep Dolly and since then CNR has been successfully used to generate clones of other animal species

Chimera  In experimental embryology, the term 'chimera' refers to a single individual made by combining two or more embryos, or mixing pluripotent cells from more than one embryo, either of the same or of another species

Cytoplasmic hybrid embryos  The term used in this report to describe embryos created through somatic cell nuclear transfer into enucleated ova, and specifically in relation to recent applications from researchers at King's College London and Newcastle University to create such entities through transfer of human genetic material into enucleated animal ova.

Differentiate  The term used to describe the progressive cellular changes required to become a more specialized cell type and the process cells undergo as they mature into normal cells. Differentiated cells have distinctive characteristics and perform specific functions

Deoxyribonucleic acid (DNA)  The material inside the nucleus of cells that carries genetic information

Embryo  An animal in the early stage of development before birth. In humans, the embryo stage is the first three months following conception

Enucleated animal ovum (EAO)   An egg from which the nucleus has been previously removed

Eukaryotic cell  A cell which contains a nucleus and other membrane-bound organelles (e.g. mitochondria)

Hybrid  1. Offspring produced from mating plants or animals from different species or varieties. 2. cell produced by fusing cells of two different origins, usually of two different species. Usually referred to as 'somatic cell hybrid'. 3. In the context of this inquiry, the term 'hybrid' is used to describe the creation of an embryo after implanting human DNA into an enucleated animal ovum.

Gametes  Male or female reproductive cells i.e. the sperm or the egg

In vitro  Literally, "in glass." The term used to refer to experiments performed in a test tube or other laboratory apparatus.

In vitro fertilisation (IVF)  A method of assisted reproduction involving combining an egg with sperm in a laboratory dish. If the egg fertilizes and begins cell division, the resulting embryo can be transferred into the woman's uterus where it may implant in the uterine lining and develop.

In vivo  Refers to biological processes that take place within a living organism or cell and is the term used to describe experiments carried out in living organisms

Mitochondria  Structures (found within the cell) responsible for providing the cell with energy. Mitochondria have their own DNA, distinct from the nuclear DNA in the cell.

Morula  The ball of cells which forms at about 4 days after insemination of the egg.

Mutant cell  A cell which differs from the wild type because it carries one or more genetic changes in its DNA.

Nucleus   The part of the cell that contains the majority of the genetic material (DNA).

Ova (plural), Ovum (singular),

Oocyte (additional term)        A female sex cell, or egg

Pluripotency   The ability to develop into multiple cell types

Preimplantation Genetic Diagnosis (PGD)  A technique in which embryos are tested for specific genetic disorders before being implanted into the uterus.

Somatic  Any type of cell other than that used in reproduction (i.e. egg or sperm)

Somatic cell nuclear transplantation (SNCT)   The process by which a cell nucleus is removed and placed into an enucleated animal ovum

Stem Cell  Cells that can give rise to other types of cells; they are produced both during embryonic development and in the adult body.

Therapeutic cloning  The use of somatic cell nuclear transfer to produce embryonic stem cells suitable for differentiation into tissues that are a perfect match to treat disease in the person who provided the cell nucleus used.

Wild-type cell  The normal, non-mutant form of a cell

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