Wells D
AFRC Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian, Scotland UK.
Methods Mol Biol. 1993;18:217-37. doi: 10.1385/0-89603-245-0:217.
Embryonic stem cells are undifferentiated cells derived from early mouse embryos, which under appropriate culture conditions proliferate continuously in vitro. ES cells have been demonstrated to be pluripotent in vivo from their capacity to form teratocarcinomas and germ-line chimeric mice, dependent on the environment into which the stem cells are introduced. When ES cells are introduced under the kidney capsule, in vivo differentiation is chaotic with the teratocarcinoma composed of a wide variety of different cell types. If, however, the stem cells are returned into a preimplantation mouse embryo, in vivo differentiation proceeds in a normal and organized manner, and the ES cells colonize the three primary cell lineages of the developing embryo: the primitive ectoderm, endoderm, and mesoderm. This leads to the formation of chimeric offspring composed of cells of two different genetic constitutions: the host embryonic cells and those derived from the ES cells. The ES cells are capable of contributing to every tissue in the fetus, including the primordial germ cells. Furthermore, the trophectodermal and primitive endodermal derivatives in the extraembryonic tissues of the conceptus may also be colonized by ES cells. Recent studies have shown that murine ES cells are capable of supporting complete fetal development, following the aggregation of stem cells with tetraploid-cleavage-stage embryos.
胚胎干细胞是源自早期小鼠胚胎的未分化细胞，在适当的培养条件下可在体外持续增殖。通过形成畸胎瘤和种系嵌合小鼠的能力，胚胎干细胞已在体内被证明具有多能性，这取决于干细胞被引入的环境。当胚胎干细胞被引入肾被膜下时，体内分化是混乱的，畸胎瘤由多种不同类型的细胞组成。然而，如果将干细胞重新植入植入前的小鼠胚胎中，体内分化会以正常且有组织的方式进行，并且胚胎干细胞会定殖于发育中胚胎的三个主要细胞谱系：原始外胚层、内胚层和中胚层。这导致形成由两种不同遗传构成的细胞组成的嵌合后代：宿主胚胎细胞和源自胚胎干细胞的细胞。胚胎干细胞能够对胎儿的每个组织做出贡献，包括原始生殖细胞。此外，胚胎干细胞也可能定殖于孕体胚胎外组织中的滋养外胚层和原始内胚层衍生物。最近的研究表明，在干细胞与四倍体卵裂期胚胎聚集后，小鼠胚胎干细胞能够支持完整的胎儿发育。
