Necessary clarifications

Dr. Irving sent me the new article on Lifeissues.net by Dr. C. Ward Kischer, a human embryologist who has been speaking out about the terminology used by proponents of abortion and genetic engineering for years.

Dr. Kischer reminds us that the cells in the early embryo are totipotent. In fact, for a while -- and no one knows for sure whether the limit is at 2 cells or 100 -- the embryo can be divided into 2 or more embryos - each of which will develop just as their brothers and sisters - as each of us did in our early days.

(Not many people are aware of "identical" quadruplets and triplets. take a look here for names of some famous multiples.)


So, one point to be stressed is that those early embryonic cells are not simply "stem cells." Some or all of them may be destined to become individual human organisms. (i.e., "people")


By the time the embryo is identifiable as a "blastocyst," however, there's no doubt that the young human - who might be destined for "disaggregation," per the latest terminology, is more than a "clump of cells.

By definition, the blastocyst is an embryo and it is the stage of life when an embryo is spherical.

But, it's not really a "hollow ball." The "embryonic stem cells" that are being harvested (or undergoing "explantation" in the lab rather than "implantation" as they would in vivo) are the "inner cell mass" of the embryo. The external, spherical layer, the trophoblast (most simply and easily thought of as the future placenta) must be removed before the inner layer - already partially differentiated - can be harvested.

However, as I pointed out last week, there is now evidence that from the first penetration of the oocyte by the sperm, besides having a new, unique, genome, the embryo is already differentiating into "top" and "bottom."

So, the second clarification is that the embryo is never just an homogenous clump with interchangable spare parts. The embryo is always an individual organism - some of whom have the probability or tendency to become multiple individuals.

The last necessary clarification is one that philosophers, theologians and scientists - and ultimately, politicians - only need in light of cloning and further manipulations of human cells that will be the beginnings of new individuals - perhaps even new types or species of individuals.

How will we define those individuals who have some human DNA - when one of their parents is a human being, but the other is (or others are) not? When artificial genes, chromosomes and then cells derived from these constructs are used, how will we define the resulting organisms? Will they be human?

No one would call the genetically engineered E. coli bacterium which, by means of Recombinant DNA produces human insulin, a "human being." Nor is there any doubt about artificial chimera such as SCID-hu mice.

However, what will we call an upright hominid whose genetic parents include one of us?