The ability to produce a wide variety of cell types (pluripotency) makes the stem cells the most important regenerative reserve in the body, which is used to fill defects arising due to various circumstances.For those who have read stem cells free sample research paper topic, the presence of stem cells in the central nervous system may seem particularly surprising.
Stem cells is the hierarchy of particular cells in living organisms, each of which can subsequently change (differentiate) in a special way (i.e., get the specialization and further develop as a normal cell).
Stem cells can divide asymmetrically, so that when the cells are dividing, there is a cell identical to the parent cell (self-reproduction), as well as a new cell, which is able to differentiate.
‘Stem cells’ are primitive cells with the capacity to divide and give rise to more identical stem cells or to specialize and form specific cells of somatic tissues.
Broadly speaking, two types of stem cell can be distinguished: embryonic stem (ES) cells which can only be derived from pre‐implantation embryos and have a proven ability to form cells of all tissues of the adult organism (termed ‘pluripotent’), and ‘adult’ stem cells, which are found in a variety of tissues in the fetus and after birth and are, under normal conditions, more specialized (‘multipotent’) with an important function in tissue replacement and repair.h ES cells are derived from the so‐called ‘inner cell mass’ of blastocyst stage embryos that develop in culture within 5 days of fertilization of the oocyte (Thomson., 2000).
Human embryonic stem cells (h ES cells) are currently discussed not only by the biologists by whom they were discovered but also by the medical profession, media, ethicists, governments and politicians. On the one hand, these ‘super cells’ have a major clinical potential in tissue repair, with their proponents believing that they represent the future relief or cure of a wide range of common disabilities; replacement of defective cells in a patient by transplantation of h ES cell‐derived equivalents would restore normal function.
On the other hand, the use of h ES cells is highly controversial because they are derived from human pre‐implantation embryos.
Evidence is strongest in animal experiments, but is increasing in humans, that adult stem cells originating in one germ layer can form a variety of other derivatives of the same germ layer (e.g.
bone marrow‐to‐muscle within the mesodermal lineage), as well as transdifferentiate to derivatives of other germ layers (e.g.
In humans, h EG cells were first established in culture in 1998, shortly after the first h ES cells, from tissue derived from an aborted fetus (Shamblott., 2001).
In the adult individual, a variety of tissues have also been found to harbour stem cell populations.