A hugely important bioethical issue
Defining which biological entity can be considered a human embryo is an outstanding bioethical issue, since it can be manipulated depending on whether it is recognised as so or not. This affects a great many biomedical practices, especially in the ethical assessment of the use of embryonic stem cells.
Tree biological entities
There are essentially three biological entities to which the condition of human embryo may be attributed: those obtained by natural fertilisation, those derived from human cloning, and the “parthenotes”, which are generated by activating the division of a non-fertilised ovum.
The requirement in order for each of the aforementioned biological entities to be considered as a human embryo, is that a living human being can be developed from it.
That this is the case with those obtained by natural fertilisation is beyond doubt. There is a larger question with respect to those obtained by cloning (somatic nuclear transfer), since although they have the complete genetic makeup characteristic of human beings, it has not hitherto been possible to confirm whether living human beings can be produced from them. This has,however, been achieved in various types of mammals (we need only remember Dolly the sheep) and non-human primates, such as those achieved by Mitalipov’s team in Oregon (USA). It even appeared that in April 2013, this same team managed to produce human blastocysts, from which they were able to derive functioning human embryo stem cell lines, although for obvious ethical reasons, the blastocysts obtained were not transferred to a woman to see if a pregnancy and birth of a child could be achieved.
The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.