Scientists in Britain said they have discovered the point at which an embryonic cell becomes a stem cell. Cambridge scientists said they discovered the determination of stem cells occurs earlier than the fourth cleavage, which is where scientists had believed the determination was made, ScienceDaily.com said.
Researcher Magdalena Zernicka-Goetz said evidence suggested differences between the embryonic cells are already set by the fourth stage, before they are partitioned between the inside and outside of the embryo. The differences, she said, depend on the orientation and order of the very first cleavage divisions of the embryo.
After fertilization, researchers said embryonic cells undergo equal, symmetrical divisions and unequal, asymmetrical divisions that direct smaller cells toward the embryo's interior, where they become the inner cell mass of stem cells.
"Our findings were surprising since they showed that cells of the mammalian embryo first start to differ from each other much earlier in development than previously supposed, Zernicka-Goetz said, "but also they give us a real clue on how to manipulate embryonic cells so that they will develop with the properties of the natural stem cells of the embryo."
The findings were reported in the journal Nature.
Source: United Press International
