Finding Embryonic Stem Cells

It is quite simple to find stem cells in fertilised human eggs (early stage embryos). The egg develops into a morula (a small mass of cells) and then into a blastocyst, a hollow ball of cells with a clump of cells inside the ball. These inner mass cells are stem cells, and are quite easy for scientists to identify and remove.

Removing the stem cells means that the embryo dies and will never develop into a baby. Many people think that using embryonic stem cells should not be allowed. Because of this problem, a lot of stem cell research uses adult stem cells, even though they are much harder to find. The PurStem project uses only adult stem cells.