We must not forget that there are two basic methods to clone human beings:
a/ somatic cell nuclear transfer which can produce unlimited copies of one individual, and
b/ embryo splitting which can only produce up to four copies.
In the latter technique, which is safer and more natural than the former, the sperm and egg from the parents combine to
become a zygote which begins to divide into cells (blastomeres) by meitosis. About five days after fertilization the zygote
becomes a blastocyst which consists of around eight blastomeres.
At this stage a scientist can remove four blastomeres using an aspirating pipette, and place them into another empty embryo to make monozygotic identical twins. Cloning by this blastomere biopsy
method, although successful in farm animals, appears to be unsuitable
for primates.
A second method to produce clones by embryo splitting is to microsurgically divide them using a surgical microblade. This is known as embryo bisection. Blastocysts, consisting of the inner cell mass and trophectoderm, are cut into two, thus creating clones. However, this embryo bisection technique as used by vets is yet untested in humans.
In conclusion, preliminary studies indicate that human embryo splitting results in more clones, however the quality of the
clones is not as good as the original blastocyst yet.
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