Glossary

Adult stem cells, Is an undifferentiated cell, which can be found in tissue or organs that can renew themselfes. This means that the adult stem cell can yeild some or all of major specialized cell types in the site were it is found.

Blastocyst, A blastocyst is the clump of cells formed five days after fertilization. The cells in the blastocyst can be divided into two groups. Those at the edges, giving the blastocyst a spherical shape, and the inner cell mass, which will later form the embryo. The outer layer will form the placenta. At this stage the cells have not yet started differentiating, and can in theory become any cell type.

Cell line, is a group of constantly dividing cells. They are obtained from human or animal tissue and can replicate in vitro for a long period of time. One of the more common cell lines is HeLa, which was obtained from Henrietta Lacks, who died of cervical cancer in 1951.

Embryo, Five days after fertilization the cell clump divides into an outer layer and an inner cell mass. The inner cell mass becomes an embryo, before it turns into a fetus.

Embryological primitive streak, A structure formed during the early embryonic development which marks the point when the clump of cells turn into embryo and placenta.

Embryonic stem cells, This is the another term for pluripotent stem cells.

Hematopoietic stem cells, Multipotent stem cells that give rise to all blood cell types.

In vitro fertilization (IVF), IVF simply means fertilization in a dish. This is achieved by obtaining sperm and an egg. Optimal eggs are chosen, and the sperm washed. They are then mixed in a dish, and cultured for approximately 3 days, until the zygote consist of 6 to 8 cells. The zygote is then transferred into the woman’s uterus, and hopefully it will implant.

Induced pluripotent stem (iPS) cells, Artificially pluripotent stem cells derived from a non-pluripotent cells by inducing expression of specific genes. See pluripotent stem cells.

Macula, An oval-shaped pigment spot in the back of the eye. Cells in the macula detect change in light and color, and is responsible for high resolution vision.

Mesenchymal stem cells, Adult stem cells that can differentiate into a variety of cell types like bone cells, cartilage cells and fat cells.

Moratorium, A moratorium means to postpone the decision-making process considering an amendment or a bill. Technically, moratorium means to delay an activity, and can therefore also apply to payments, i.e. on a loan.

Multipotent stem cells, These cells are extracted from human tissue and can give rise to almost all cells in the tissue from which it originated.

Oligodendroglia, A type of brain cell, which main function is to isolate the axons, the long projection of a nerve cells in the central nervous system.

Oocyte, Immature egg cell.

Pluripotent stem cells, These cells can develop into any of the cells found in adult organisms and are formed from the inner cell mass in the blastocyst, about 5 days after fertilization. These are among the most important in stem cell research because they can be changed and developed into specific tissues for therapeutic purposes; to help damaged body parts heal; form new tissue among others.

Reproductive cloning, The manipulation of genetic material in order to achieve the reproduction of a human being and includes nuclear transfer or embryo splitting for such purpose. The living being is a genetic replica of the source of genetic material.

Retinal cells, Cells from the back of the eye, where also the macula is situated. This tissue is light-sensitive.

Somatic cell nuclear transfer, A lab technique where the nucleus of a somatic cell (a body cell other than a sperm or egg cell), which contains the organism’s DNA, is taken out. The nucleus is then inserted into denucleated egg cell and stimulated to divide, forming a blastocyst (early embryo) with identical DNA as the original organism.

Somatic stem cells, This is the academic term for adult stem cells.

Therapeutic cloning, The manipulation of genetic material from either adult, zygotic or embryonic cells in order to alter the functions of cells or tissues for therapeutic purposes.

– Totipotent cells, These cells can divide and can create all differentiated cells in an organism. Totipotent cells exist after fertilization and before the creation of the blastocyst. This means that the cells can become the placenta and/or part of the extra-embryonic membranes.

Umbilical cord, This is the cord connecting the fetus with the placenta. In the cord there is a blood flow, supplying the fetus with oxygenated, nutrition-rich blood from the blood, and returns the used blood. Blood from the cord and the placenta have been found to produce new blood cells, and are therefore interesting in stem cell research.

Zygote, A zygote is the fertilized egg.

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