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Cell potency is a cell's ability to differentiate into other cell types. The more cell types a cell can differentiate into, the greater its potency. Potency is also described as the gene activation potential within a cell which like a continuum begins with totipotency to designate a cell with the most differentiation potential, pluripotency, multipotency, oligopotency and finally unipotency. Potency is taken from the Latin term "potens" which means "having power." ==Totipotency== Totipotency is the ability of a single cell to divide and produce all of the differentiated cells in an organism. Spores and Zygotes are examples of totipotent cells. In the spectrum of cell potency, totipotency represents the cell with the greatest differentiation potential. ''Toti'' comes from the Latin ''totus'' which means "entirely." It is possible for a fully differentiated cell to return to a state of totipotency. This conversion to totipotency is complex, not fully understood and the subject of recent research. Research in 2011 has shown that cells may differentiate not into a fully totipotent cell, but instead into a "complex cellular variation" of totipotency. The human development model is one which can be used to describe how totipotent cells arise. Human development begins when a sperm fertilizes an egg and the resulting fertilized egg creates a single totipotent cell, a zygote. In the first hours after fertilization, this zygote divides into identical totipotent cells, which can later develop into any of the three germ layers of a human (endoderm, mesoderm, or ectoderm), into cells of the cytotrophoblast layer or syncytiotrophoblast layer of the placenta. After reaching a 16-cell stage, the totipotent cells of the morula differentiate into cells that will eventually become either the blastocyst's Inner cell mass or the outer trophoblasts. Approximately four days after fertilization and after several cycles of cell division, these totipotent cells begin to specialize. The inner cell mass, the source of embryonic stem cells, becomes pluripotent. Research on ''Caenorhabditis elegans'' suggests that multiple mechanisms including RNA regulation may play a role in maintaining totipotency at different stages of development in some species. Work with zebrafish and mammals suggest a further interplay between miRNA and RNA binding proteins (RBPs) in determining development differences. In September 2013, a team from the Spanish national Cancer Research Centre were able for the first time to make adult cells from mice retreat to the characteristics of embryonic stem cells thereby achieving totipotency. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cell potency」の詳細全文を読む スポンサード リンク
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