Stem cell/stem cell/stem cells
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A stem cell is a cell found in all multicellular organisms that possesses two properties :
- it can self-renew to produce more stem cell
- it can differentiate into diverse specialized cell types.
Several types of stem cells are distinguished :
- The totipotent stem cells are the cells of the embryo from the fertilized egg stage to the eight-cell stage ; they can differentiate into all the embryonic and extraembryonic cell types and construct a complete, viable organism.
- The pluripotent stem cells are the daughter cells of the totipotent cells and can differentiate into all the types of cells with the exception of the extraembryonic cell types ; they can give cells derived of any of the three germ layers (endoderm, ectoderm, and mesoderm). Pluripotency is a property of the cells that are located within the inner cell mass (ICM) of the developing blastocyst. Pluripotency in vivo and in vitro is governed by a trinity of nuclear regulators, Oct4 , Sox2 , and Nanog .
- The multipotent stem cells can give different types of cell but only those issued from a specific cell lineage
- The unipotent stem cell can differentiate into only one type of cell but they can also self-renew as all the stem cells and have to be distinguished from non-stem cells.
For more details, see :
Stem cells Wikipaedia
Chambers I, Tomlinson SR. The transcriptional foundation of pluripotency. Development. 2009 Jul ;136(14):2311-22. Review. PubMed PMID : 19542351 ; PubMed Central PMCID : PMC2729344.
Wednesday 8 February 2012
by Michel Démarchez
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