This then changes to a blastocyst, consisting of an outer layer called a trophoblast, and an inner cell mass called the embryoblast.
22.
To be more specific, they come from the inner cell mass of a blastophere, which is the beginning stage of an embryo.
23.
Some cells, however, will remain trapped in the interior and will become the inner cell mass ( ICM ), and are pluripotent.
24.
However, it remains unclear whether the cells originate from the fetus itself, the placenta or possibly the inner cell mass of the blastocyst.
25.
Mammals at this stage form a structure called the blastocyst, characterized by an inner cell mass that is distinct from the surrounding blastula.
26.
The Wisconsin patents describe the method for isolating stem cells from the inner cell mass that arises in human embryos shortly after conception.
27.
Thomson grew his embryonic stem cells from the inner cell mass of blastocysts left over from a fertility treatment and due to be discarded.
28.
At the beginning of the second week, a cavity appears within the inner cell mass and when it enlarges it becomes the amniotic cavity.
29.
Mouse embryos that are Oct-4-deficient or have low expression levels of Oct-4 fail to form the inner cell mass, lose pluripotency and differentiate into trophectoderm.
30.
Inside the embryo, which at this stage is just a hollow sphere, rests a clump of about 100 cells known as the inner cell mass.
