A cell and immunity
　Our cell looks the same as other persons' cell to look at .
　

As you see in the animation below, Mr. A's cell and Mr. B's cell viewed under a microscope are almost the same. The cell here expresses an epithelial cell which covers the surface of the skin and internal organs.
　However, when a cell is looked finely, it is up to persons. There is a different mark on the surface of people's cell as well respectively as a fingerprint is different by a person each.

Others' cell and one's cell are by no means the same even if there is a difference in degree.
In other words, oneself is oneself. Another person cannot become oneself
　The mark is called a MHC class 1 molecule. When we make a difficult talk, this is a protein which is made from the gene called major histocompatibility complex, MHC
One cell of the pancreas
　Furthermore, the animation below shows that MHC class 1 molecules are very small.
There are many on the surface of the cell.
　In addition, we compare the each cell and a MHC class 1 molecule to an enlarged face and a crown and express from the next animation since it is incomprehensible in these figures.

ミトコンドリア：mitochondria、鞭毛：flagella、核膜：nuclear membrance、染色質：chromatin、核小体：nuclear body、核：hilum、リボソーム：ribosome、粗面小胞体：granular endoplasmic reticulum、細胞膜：cell wall、滑面小胞体：smooth endoplasmic reticulum、ゴルジ装置：golgi apparatus、リソソーム：lysosome、微小管：microtubule、中心帯：central zone、」ペルオキシソーム：microbody、微小線維：microfilament

The cell is expressed with a different face each. A crown on the head expresses a MHC class 1 molecule. For example, in the case of Mr. A, a crown is the same even if the kinds of cell differ.

 
Mr. A’s cell　

Mr. B’s cell

There is an each MHC class 1 molecule in the cell of Mr. A and Mr. B, i.e., all human cells. However, there are the strength and weakness in the effect of the mark which means one's cell is a thing only for oneself.

For the details, please refer to http://ja.wikipedia.org/wiki/MHC#MHC.E5.88.86.E5.AD.90.
On the observer’s left is Mr. A’s cell, and right is Mr. B’s. It is the almost same cell. If Mr. A’s cell goes to Mr. B, Mr. A is sent back like an animation. Even Mr. B goes to Mr. A, Mr. B is sent back.
Let’s think about the mechanism to send back next time.
Since the decoration (crown) of the head that is MHC class 1 molecules is different, they do not adhere like a friend each other.


It is related to a transplant.

Others' skin is transplanted to one’s skin, that is, implanting is fundamentally impossible.
It is because the crown is different.



　

Although a certain skillful workmanship is likely to enable the transplantation these days, it is carried out by considering this MHC class 1 molecule.