英語(yǔ)時(shí)差:干細(xì)胞，幫助白血病患者

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Stem Cells That Help Leukemia Patients Y:Hey,Don,name three types of stem cells in your body? D:I've thought stem cells were from Embryos, Yael,do adult have them,too? Y:We’ve got a few kinds of stem cells, each with a different role.The term “potency” is used to describe the capacity of cells to change, or differentiate, into different cell types when they divide. There are totipotent, pluripotent, multipotent, oligopotent and unipotent cells. D:Wow!How about some examples? Y:Sure,a fertilized egg cell as it divides makes every kind of cell in the human body. That one cell can create an entire person. So a fertilized egg is an example of totipotency.Embryonic stem cells are almost as flexible. They can differentiate into almost any cell type, like lung, muscle, liver, skin or brain cells. But a single embryonic stem cell can never grow into an entire organism. This is an example of pluripotency. D:My friend had a Stem Cell Transplants as a treatment for leukemia.What kind of stem cells of those? Y:She probably received a donation of blood stem cells, like those found in bone marrow.Blood stem cells are multipotent. They can make all the different blood cell types, like red and white blood cells or platelets. But they can’t create other kinds of cells. An example of oligopotency lurks in your lymph nodes. Lymphoid stem cells can produce a few, but not all, kinds of blood cells.Finally, cells that only produce identical copies of themselves are called unipotent. Like skin cells, when they divide, they only make more skin cells.