In order to escape legal restrictions, such as the 14-day rule , and numerous other moral and ethical concerns, many of the scientists busy creating human embryos by means of new technologies are also busy creating new terms to describe their creations - terms designed to imply that no human individual has been created.
In order to understand the obfuscation in recent literature, it is helpful to know basic terms in embryology:
The result of the fusion of an egg cell and a sperm cell (i.e. conception) is a one-cell embryo called a zygote . At conception, a new, distinct, self-directing human individual exists.
During the next 5 to 14 days, the embryo is called a blastocyst . In this window, the embryo's inner cell mass will divide into multiple cells and the embryo will implant in the uterus.
Knowledge of the methods of cell manipulation are also needed:
In-vitro Fertilization (IVF) : The creation of a zygote in a laboratory dish. IVF allows research and manipulation of the human individual at the embryonic stage of development.
Somatic Cell Nuclear Transfer (SCNT or "Cloning") : The nucleus (with complete genome) of a somatic cell (such as a basic skin cell) is transferred into an enucleated egg cell (the genetic material of the egg cell has been removed). The resulting human embryo is genetically identical to the donor of the somatic cell.
Embryonic Stem Cells (ES) : stem cells extracted from embryos in a laboratory causing their destruction.
Induced Pluripotent Stem Cells (iPS) : stem cells that have been obtained by reversing a differentiated cell back to its original stem cell state by the use of a virus.
Twenty years ago, the question would have been easily answered: an embryo is a new human being resulting from the fusion of sperm and egg cells, the good-old-fashioned way . Today, however, a human embryo can be generated without the direct contribution of either.
An abstract of an article published in 2006 by Nobel-prize-winning stem cell researcher Shinya Yamanaka reads as following:
Differentiated cells can be reprogrammed to an embryonic-like state by transfer of nuclear contents into enucleated oocytes [(egg cells)] or by fusion with embryonic stem (ES) cells…. These cells, which we designated iPS (induced pluripotent stem) cells exhibit the morphology and growth properties of ES cells… (emphasis added)
The process for obtaining IPS cells requires the action of a virus in order to induce the cell back to its pluripotent state. However, in 2007 Yamanaka published a further articulation on IPS cell's similarity to embryonic stem cells but without noting whether or not an embryo was used to obtain them.
Regardless of whether the IPS cells were made using an e-nucleated egg or embryonic stem cells, or even other means, what results could be an embryo with all of the properties identical to an embryo obtained through the fusión of egg and sperm. Though this multiplication of methods all end in the same result, the differences in means have proven convenient for those who want to use language to obscure the reality of their science. Thus Yamanka's use of the phrase embryonic-like state rather than embryo.
Below are a few more examples of terms based more on means than ends:
" Clonotes " (proposed by McHugh and Jaenisch): "Human SCNT blastocysts, if they were ever successfully created, ought be called "clonotes" rather than "zygotes" or "embryos."
" Embryo-like artifacts " (offered by the President's Council on Bioethics, 2005) for Human SCNT blastocysts deemed not to survive.
And more recently:
" Synthetic human entities with embryo-like features " ( SHEEFs ). The generation of an embryo from human pluripotent stem cells using the cloning technique.
These new terms depart from previous scientific literature and muddy traditional terminology by referring not to the embryo created but to the embryo-like character of the cells used to create it.
Several arguments to support such position are made, among them:
Human blastocysts created by SCNT are, by definition, not derived from the union of sperm and egg. Some consider this difference enough reason not to consider SCNT blastocysts as embryos.
Currently no extracorporeal (out of the human body) human blastocyst (fertilized or cloned) has even a remote chance of developing into a human being unless the choice is made to implant it into a woman's uterus. Thus SCNT human blastocysts lack both the biological potential and the circumstantial potential to become human beings.
What these arguments miss is that, physically, there is no biological difference between embryo, embryo-like and the other euphemisms employed. How different are human SCNT blastocysts from fertilized human embryos in terms of potential to complete human life? They are identical . The only difference is semantic. Whatever the technology, the result is the same: an embryo.
To say that cloned human blastocysts lack the capacity for normal, healthy development is not the same as saying that they are not human embryos. The fact that one to three percent of cloned animal blastocysts survive to birth proves that those blastocysts went through all the stages of embryological development.
Furthermore, there is no biological foundation for limiting the definition of embryos only to those capable of surviving and being implanted. Human beings are not defined by the location or means of our creation. Those are mere circumstances - though not without ethical consequences themselves. To belong to the human species one needs only a complete individual genome that orchestates an autonomous and uninterrupted human development.
Similarly, the term pre-embryo was developed in the 1992 paternity case Davis v. Davis as a means to avoid the treatment of frozen embryos in custody cases. We are again in the same arena, trying to avoid our obligation to respect the dignity of human life at all stages by means of redefining life itself.