The following well-established human embryology textbooks document the well-known scientific facts concerning the early development of the human being: (all emphases used in quotes from the following textbooks below are mine)
-- Furton and Matthews-Roth: "Personhood is not an issue here." (par. 1, "Response")
-- My response: I hope that I have sufficiently explained in Part I that "personhood" is THE issue here. The human embryology is useful only insofar as it can be used to scientifically ground a specific philosophical concept of "delayed personhoos". Thus in these debates the human embryology and the philosophical concept of "personhood" are really two sides of the same coin. They are inseparable issues, since one depends on the other. For example, McCormick clearly states the connection between the human embryology and the philosophical concept of "delayed personhood" in his article, where he is trying to make a real distinction between a "genetic individual" (i.e., a "pre-embryo) and a "developmental individual" (i.e., a "person):
I contend in this paper that the moral status -- and specifically the controversial issue of personhood -- is related to the attainment of developmental individuality (being the source of one individual) ... As we will see, that does not occur until a single body axis has begun to form near the end of the second week post fertilization when implantation is underway. ... [McCormick next gives his reason why this blastocyst is not an embryo or person, but only a "pre-embryo" - DNI] This multicellular entity, called a blastocyst has an outer cellular wall, a central fluid-filled cavity and a small gathering of cells at one end known as the inner cell mass. Developmental studies show that the cells of the outer wall become the trophoblast (feeding layer) and are precursors to the later placenta. Ultimately, all these cells are discarded at birth.3
McCormick's POINT is philosophical, i.e., somehow, because of his (and Grobstein's) own perceived "separation" or "isolation" between the inner and outer cell layers of the blastocyst, this translates for them into a scientific grounding for a philosophical claim -- i.e., that there was no "developmental individual" there yet -- i.e., so "person". Therefore, e.g., these early blastocysts were simply just "pre-embryos".
As with McCormick and Grobstein, virtually all of the secular bioethicists' arguments for "delayed personhood" which I addressed in my dissertation and other work likewise use "scientific" facts about early human development in order to ground their philosophical concept of "personhood" and justify their moral positions on this issue. The same is true for the arguments of NIH, NBAC, of legions of others, and as articulated in various laws, regulations and legal briefs.
The apparent inability of Furton and Matthews-Roth to understand the significance of the "personhood" issue inherent in the human embryonic stem cell research issue probably explains a number of other errors they make in their "Response". If they are not familiar with the last 30 years of secular bioethics issues pertaining to human embryo and fetal research, "delayed personhood", etc., then they will not understand the significance of certain patterns of argumentation or redefinitions of basic scientific and philosophical terms used for so long by bioethicists, or why certain very specific and characteristic scientific facts about human embryology are indeed intimately connected with these moral debates. They may think that all they are addressing is the human embryology relevant to the human embryonic stem cell issue. But the specific human embryological facts which they select -- many of which are actually incorrect -- fall into a 30-year long pattern of fraudulent facts about early human development which have been used by hundreds of secular bioethicsts and others -- indeed, many within the Church -- by now to argue for "delayed personhood" and therefore the use of these early human embryos in destructive experimental research as morally acceptable.
In sexual reproduction, the human embryo begins at fertilization as a single-cell zygote; the human embryo from fertilization through 8 weeks is simultaneously and continuously a human being, an individual, an organism, genetically a male or female. The human embryo, the human being, the human individual, does not just exist as the inner cell mass in the later blastocyst stage. The whole blastocyst is the embryo, the human being -- not just the cells from the inner cell mass.
-- Furton and Matthews-Roth: "The division into an inner and outer layer of cells is an important feature for moral analysis because the OUTER CELLS, though they are vital for the continued existence of the embryo, ARE NOT THE EMBRYO ITSELF ... Embryonic stem cells, however, do not come from the outer layer of cells but from THE INNER CELL MASS (THE EMBRYOBLAST), AND THESE ARE THE ACTUAL CELLS OF THE DEVELOPING HUMAN BEING." ( par. 10 and 11, original article). "In the summary of chapter 2, M&P [Keith Moore and Persaud] describe the blastocyst as consisting of the INNER CELL MASS OR EMBRYOBLAST, WHICH GIVES RISE TO THE EMBRYO ....". (par. 3, "Response") (emphases added)
Yet Furton and Matthews-Roth actually contradict themselves when they also state (quoting from Moore and Persaud's 5th edition): "When an ovum is fertilized by a sperm, the resulting cell is called the zygote: this cell is 'the beginning of a new human being'". (par. 7, original article) (emphases added)
-- My response: These are very contradictory statements. In one statement they claim that there is a human being or human embryo present, but only as the inner cell mass of the 5-7 day blastocyst. Obviously, then, the whole blastocyst per se is not the human being or human embryo. Then they refer to the inner cell mass as that which gives rise to the embryo -- implying that the embryo isn't there yet. So let's consider for a moment where these statements of Furton and Matthews-Roth could lead.
Once again, if it is true (which it is not) that the whole blastocyst is not the human being or human embryo, and if only the cells of the inner layer are the human and the human embryo, then only part of the blastocyst is the human being or human embryo. One could then argue that the use of abortifacients which only effect the outer cell layer is ethical, since they are not directly affecting the "embryo" -- i.e., the inner cell mass. One could also argue that these blastocysts are not "developmental individuals" yet -- i.e., they are still just a mixture of isolated inner and outer cells; they are just "pre-embryos" (as McCormick et al have argued) -- and therefore the "pre-embryos" can ethically be used in all sorts of experimental research.
Or, if it is true (which it is not) that the human embryo only comes to be from the inner cell mass "which gives rise to the embryo", then the human embryo isn't there yet, so even the blastocyst must be a "pre-embryo". And if the inner cell mass does not form until after at least 4 days post fertilization, then this leaves the door wide open for a "pre-embryo" argument for all of the stages of the developing human before 4 days as well (e.g., the zygote, the morula, etc.) -- none of whom could possibly be embryos yet since no distinct inner cell mass has formed yet. The only difference between the McCormick/Grobstein and the Furton/Matthews-Roth statements is that the former include the blastocyst as a "pre-embryo", whereas the latter allow (in one of their contradictory statements, that is) for at least a part of the blastocyst (the inner cell layer) as a human embryo and human being. Still, in both statements, everything that comes before the blastocyst (e.g., the zygote and the morula) could be fair game. Why is this ruse so difficult to see? It has been done for decades. The bioethics libraries are full of such articles and arguments for "delayed personhood".
Whether or not Furton, Matthews-Roth, or anyone else want to insist that they would not make such arguments is irrelevant. Others far more influential in these debates than them have and still continue to do so every chance they get.
Furthermore, in their own words, Furton and Matthews-Roth are clearly well aware of the importance of their above statements for doing any moral analysis, since they use these very terms themselves -- and hence they must also be aware of the connection between the human embryology and the moral philosophical concepts.
I would argue, contra Furton and Matthews-Roth, that the whole blastocyst is the embryo, the human being -- not just the inner cell mass -- and that the individual human embryo and human being normally exist first as such at fertilization -- not after the formation of the primitive streak (14-days). For documentation in support of ISSUE B as stated above, and of my response, I quote from the four human embryology textbooks listed above (all emphases are mine; all textbooks are in concert with the international nomenclature for human embryology):
-- Furton and Matthews-Roth: (countering my comment that the blastocyst enters the uterus, and quoting from Moore and Persaud) "Shortly after the morula enters the uterus ..." ... and "About three days after fertilization, a ball of about 12 or more blastomeres, called a morula, enters the uterus".
-- My response: Furton and Matthews-Roth are correct to point out that sometimes the morula does enter the uterus. But although different human embryology textbooks state different "facts", especially in very early development, of the four texts I checked it is only Moore and Persaud who state this. O'Rahilly and Muller, and Carlson do not state if it is the morula or the blastocyst, but only use the phrase "the embryo enters the uterus". Larsen uses the term "blastocyst". The reality is more likely that it depends on circumstances relating to the unique characteristics of the mother, or on which stage the embryo is at as it enters the uterus -- sometimes it is the morula, sometimes it is the blastocyst. At any rate, I quote from the following human embryology textbooks in support of my comment that the embryo at the blastocyst stage does enter the uterus:
-- LARSEN (1997): By the 30-cell stage, the embryo, now called a morula, begins to form a fluid-filled central cavity, the blastocyst cavity. By the fifth to sixth day of development, the embryo is a hollow ball of about 100 cells called a blastocyst. At this point it enters the uterine cavity and begins to implant into the endometrial lining of the uterine wall. (p. 3)
-- ibid.: Very soon after arriving in the uterus, the blastocyst becomes tightly adherent to the uterine lining. (p. 20)
-- MOORE AND PERSAUD (1998): Successful transfer of four- to eight-cell embryos and blastocysts to the uterus after thawing is now a common practice. (p. 39)
-- Furton and Matthews-Roth: "Contrary to what the reader states, Siamese twins arise because the embryonic disc does not completely divide, or adjacent ones fuse ... and develop within 2 to two and one-half weeks (14-19 days) ..., not 'well after 14-days and the formation of the primitive streak', as the reader stated. The rare 'fetus-in-fetu' results from 'an unequal division of the inner cell mass after formation of the bilamellar disc' - again within this same time period ... . In fact, figure 1 of Hing's paper shows that conjoined twins and fetus-in-fetu occur before 21 days. However, Spencer suggests that some conjoined twins form during the fourth week of life (by 28 days ..., again not 'well after 14-days'". (par. 11, "Response")
-- My response: The point is that McCormick, Grobstein, and a host of others (especially theologians) use the claim that since twinning cannot take place after 14-days, all stages of the early human embryo before that are just "pre-embryos", and therefore they can be used in research, etc. This 14-day biological marker for "personhood" -- as with virtually all of these different biological markers used to argue for "delayed personhood" -- are totally arbitrary. It would also leave out of "personhood" all human beings who were "twinned" (monozygotic) before 14-days (about 35% of monozygotic twins), and it would leave out all twins that form after 14-days (e.g., some Siamese or conjoined twins, and fetus-in-fetu twins -- whether they survive or not.) That is, none of these would be "developmentally single", and therefore not "persons". This is absurd, and all one needs to do to point this out is to provide human embryological data which demonstrates that twinning can take place after this arbitrary 14-day marker (either by late division of the germ layer after 14-days, or by the subsequent engulfing or fusing of two embryos). Therefore the 14-day marker for "personhood" is scientifically invalid.
My use of the term "well after" is quite legitimate, especially given the circumstances. Consider that according to McCormick et al (including NBAC and NIH recommendations), it is "ethical" to use human embryos up to the magic 14-day marker, so there are quite a number of people who would and do sanction their use in experimental research before precisely 14-days. If you were one of those embryos you would care about such arbitrary markers, and whether or not you happened to fall just before or just after that marker -- as a monozygotic twin or otherwise. If it were me I'd be sitting there with a stop-watch! And if "developmental individuality" has not been reached until 15, 16, 17, 20, 28 days after this magic marker, then these twins would also not be considered "persons", and therefore the rationale is in place for them to be used in experimental research. If you were one of these twins, you would find it of great concern that you had passed this magic 14-day marker and yet could still be used in experimental research. One or two days for you would be a highly significant time spread. The concerns of Furton and Matthews-Roth here seem rather trite. They themselves have given scientific statements in their "Response" (par. 11) indicating that some twinning does take place up until the 28th day! Either twinning cannot take place after 14-days, or it can. Answer: it can. Therefore this "twinning" argument is scientifically unsubstantiated and therefore invalid.
In support of my claim that twinning can take place after 14-days, assuming that people understand the significance of that biological time marker, I quote from the following sources:
Extrapolating from other animal studies to human development is always cautioned against in human embryology textbooks, is common operating knowledge in professional bench research, and can lead to erroneous scientific claims.
-- Furton and Matthews-Roth: "The first two divisions of the zygote produce a total of four cells, each of which are 'totipotent' (the zygote divides into two cells, then these two divide, forming a total of four cells)." (par. 7, original article) "Pedersen et al ..., discussing early mouse development, which is similar to early human development, state that 'The mouse inner cell mass is established by cells ...". (par. 4, "Response"). "Indeed, one of the first two cells formed by the zygote's first division divides first, as in the mouse, and later the second cell divides. The asynchrony of division times really does not affect our narrative -- the cells are all still totipotent!" (par.10, "Response") (emphases added)
-- My response: Again, Furton and Matthews-Roth are self-contradictory. In their original article they state that the division of cells in the early human embryo is, essentially, synchronous (i.e., 2, 4 -- and as is often claimed by others, 8, 16, 32, etc.). I pointed out in my comments that it is actually asynchronous for human embryos. Then in their "Response" they essentially agree with me, but make it sound as if they were disagreeing with me by changing the subject and then stating that "the cells are still totipotent".
That these early cells are "still totipotent" is not the issue. Nor is it the issue that mouse cells also divide asynchronously -- other animal species don't. The issue is that it is too easy to over-generalize from one species to another, and this should be done only with great caution. Development in one species is not necessarily the same as in another species. Many of the arguments used in the secular bioethics debates -- and even in some embryology textbooks -- cite results from non-human studies perhaps a bit too excessively, and assume without experimental basis that the same facts are true in human development as in mouse or frog development. This general "dictum" will also be of significance in the next "Issue F" discussed below.
In support of this caution, and of the asynchronous cell division in human development, I quote from the following human embryology textbooks: