干细胞是非特化细胞，具有分化成各种特化细胞类型的能力. This makes them a valuable tool for research and regenerative medicine. 干细胞的来源主要有两个: 胚胎干细胞和成体干细胞.
The Origins of Stem Cells
Stem cells are derived from the inner cell mass of a blastocyst, which is a hollow ball of cells that forms during early embryonic development. The inner cell mass gives rise to the embryo proper, while the outer layer of cells forms the placenta.
干细胞的来源
胚胎干细胞 are derived from the inner cell mass of a blastocyst. These cells are pluripotent, meaning that they can differentiate into any type of cell in the body. 然而, embryonic stem cells are controversial because they require the destruction of an embryo.
成体干细胞 are found in small numbers in various tissues throughout the body. These cells are multipotent, meaning that they can differentiate into a limited number of cell types. 然而, adult stem cells are more difficult to isolate and grow in culture than embryonic stem cells.
Stem cells are a promising tool for research and regenerative medicine. 然而, the ethical concerns surrounding embryonic stem cells have led to the development of alternative sources of stem cells, such as adult stem cells.
