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ES cells
Did you understand the stem cell?
Then, we will explain embryonic stem cells.
Obtaining ES cells
A fertilized ovum repeats cleavage in the process of ontogeny, and changes to the figure of a baby gradually.
fertilized egg→2-cell period→4-cell period→8-cell period→16-cell period→morula period→blastocyst period
cleavage advances in a process such as the above.
Generally, it is said that the start of differentiation happens between the morula period and the blastocyst period.
※However, the corroboration hasn't been obtained yet, because there are various opinions about the start of the differentiation.
Divided into "cell which will build body of the fetus and the viscera"(Nutrition ectoderm), and "cell which will make organizations that help the growth of the fetus, such as placenta"(Internal cell masses) when first point of differentiation.
The cells which took out and culture this internal cell masses to the outside of the body are ES cells.
Properties of differentiate
Fetuses are made from internal cell masses. That's why ES cells can differentiate to all the cells of man's body.
However, as we explained before, differentiation is one-way ticket.
The cells that have already differentiated to internal cell mases can't differentiate to Nutrition ectoderm.
Therefore, it cannot form the placenta.
In other words, it is impossible to create life from an embryonic stem cell simple substance newly.
In this way, they have the ability to differentiate to various cells but on the other hand, it can't make up a complete individual in a simple substance called "Pluripotency".
※There is the opinion which assumes embryonic stem cells have totipotency, but we assumes that embryonic stem cells have pluripotency.
Culture ES cells and application to regenerative medicine
We ectract internal cell masses out of a body to make embryonic stem cells, and when culturing the cells they are callled "Feeder cells" .
Internal cell masses have pluripotency. That's why it becomes teratoma, and we can't make ES cells if we culture it without taking any further steps.
If we add feeder cells to internal cell masses, we can culture it without making teratoma.
Animals that are part of the body composed of cells derived from ES cells is born by returning to the blastocyst stage embryos and morula stage after the addition of genetically engineered ES cells.
The animals which are made using such a technique are called "Chimeric animal".
If female and male chimeric animals have the egg and sperm of the embryonic stem cell origin which added inheritable genetic modification, we can make animals whose cell of the body has been genetically modified.
People's genes differ from the genes of mise.
However, we can make a mouse that has genes which are near to human genes using gene-recombination technology, and we can make good use of it for medicinal research.
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