Select Committee on Stem Cell Research Report


APPENDIX 5

Glossary of biological terms used in the Report
blastocyst:a hollow ball of 50 to 100 cells reached after about five days' embryonic development just before implantation in the uterus.
cell line:cells of common descent and type cultured in the laboratory.
cell nuclear replacement   (also called somatic cell nuclear transfer) the procedure of replacing the cell nucleus of an egg with the nucleus from another cell.
cell type:one of over 200 different types of cells in the body, for example blood cells, liver cells, neural cells. Each of these cell types has a different subset of genes switched on ("expressed") and therefore specific characteristics which allow it to serve a specific function in the body.
clone:a cell or organism derived from and genetically identical to another cell or organism.
cytoplasm:a jelly-like substance, which together with the nucleus which it surrounds, forms the cell.
dedifferentiation:the process of inducing a specialised cell to revert towards pluripotency.
differentiation:the process by which less specialised cells develop into more specialised cell types—see Box 1 in Chapter 2.
DNA:deoxyribonucleic acid—the cell's and the body's genetic material.
enrichment:increasing the proportion of stem cells in a tissue sample by removing some of the non-stem cell material.
enucleated:from which the nucleus has been removed (usually of an egg).
gamete:the male sperm or female egg.
genome:the complete genetic material of an individual.
in vitro fertilisation:the fertilisation of an egg by a sperm outside the body.
mitochondria:energy-producing structures in the cytoplasm of a cell.
multipotent:having the capacity to develop into multiple (but not all) cell types.
oocyte:the female egg.
plasticity:the capacity of cells to develop into different cell types.
pluripotent:having the capacity to develop into every cell type in the human body, but not the extra-embryonic tissues such as the placenta and umbilical cord.
primitive streak:a collection of cells which appears at about 14 days after fertilisation from which the central nervous system eventually develops.
redifferentiation:the process of inducing a dedifferentiated cell to differentiate into a (different) specialised cell type.
totipotent:having the capacity to develop into every cell type required for human development, including extra-embryonic tissues.
zygote:the single cell formed when the male sperm fertilises the female egg.




 
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