Stem cells from IVF leftovers are derived by fertilizing oocytes with donor sperm, with stem cell lines obtained from the inner cell masses of blastocysts. In contrast, somatic cell nuclear transfer involves transferring the nucleus of a somatic cell into an enucleated egg, leading to the development of a zygote. Both methods yield stem cells, but they differ in their genomic sources and processes used for obtaining them.

1. Explain how stem cells obtained from IVF leftovers and somatic cell nuclear transfer differ in
terms of the sources of their genomes.
Solution
Oocytes from women were extracted and inseminated with thaed donor sperm, after the process
of insemination oocytes were successfully fertilized and developed into blastocyst stage and the
inner cell masses of the blastocyst that were removed yielded stem cell lines. From a left over
IVF, extraction of single blastomere is helpful.
In somatic cell nuclear transfer, the nucleus of a somatic cell is transferred to the cytoplasm of an
ennucleated egg which then becomes a zygote and is then allowed to develop to blastocyst stage.
Reference
1. Josefson, D. (2001). Embryos created for stem cell research.British medical journal,
323(7305), 127.