干细胞是无专门的细胞，具有发育到体内任何细胞的潜力. This makes them a valuable resource for regenerative medicine, as they could be used to treat a wide range of diseases and injuries. 然而, before stem cells can be used for therapeutic purposes, it is important to understand where they come from.
干细胞的起源
Stem cells are derived from the early embryo. During the first few days of development, the embryo is composed of a mass of undifferentiated cells called the inner cell mass. These cells have the potential to develop into any cell in the body. 随着胚胎的发展, the inner cell mass gives rise to the three germ layers: the ectoderm, the mesoderm, and the endoderm. Each of these germ layers gives rise to a specific set of tissues and organs.
干细胞来源
There are two main sources of stem cells: 胚胎干细胞和成年干细胞. 胚胎干细胞来自胚泡的内部细胞质量, which is a 5-day-old embryo. 成年干细胞在整个体内的各种组织中发现, 例如骨髓, 脐带, 和脂肪组织.
胚胎干细胞是多能的, which means that they have the potential to develop into any cell in the body. 成年干细胞是多功能的, which means that they have the potential to develop into a limited number of cell types.
The origin and sources of stem cells are important considerations for regenerative medicine. Embryonic stem cells have the potential to develop into any cell in the body, but their use is controversial due to ethical concerns. Adult stem cells are less controversial, but they have a more limited potential for differentiation. 随着研究的继续, it is likely that new sources of stem cells will be discovered, which will provide even more options for regenerative medicine.