Human embryonic stem cells that are used in research are Sel

Human embryonic stem cells that are used in research are

Select one:

a. cultured in the bodies of human embryos from outer cell mass cells.

b. cultured in laboratory dishes from inner cell mass cells taken from a 5-day embryo.

c. taken from aborted human fetuses between 10 and 12 weeks of gestation.

d. taken from stillbirths that do not have genetic diseases.

Solution

Human embryonic stem cells (hESCs) are generated by transferring cells from a preimplantation-stage embryo into a laboratory culture dish.

After fertilization, the human embryo takes around 4 days to reach the uterus through the fallopian tube and subsequently adheres or ‘implants’ itself to the wall of the uterus, a process called as implantation. On average, after fertilization, implantation occurs from 6 to 10 days. So, one can expect the embryo to be in the pre-implantation stage at 5 days. Also by this time, the embryo reaches the blastocyst stage where it develops two distinct population of cells: the outer cell mass, called the trophectoderm from which the placenta develops, and the inner cell mass, which will become the foetus.

Thus, the correct choice for the given question is:

b. cultured in laboratory dishes from inner cell mass cells taken from a 5-day embryo.