Monitoring Stem Cell Research 
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innovation aim to shift the ethical debate from the question of 
whether or when a human embryo should be considered a hu- 
man being to the question of which organized structures and 
potentials constitute the minimal criteria for considering an 
entity to be a human embryo. 
Absent all the essential elements (including a full comple- 
ment of chromosomes, proper genetic sequence and chromatin 
configuration, and cytoplasmic structures and transcription 
factors), advocates of this proposal argue, there can be no in- 
tegrated whole, no organism, and hence no human embryo. By 
technically constructing biological entities lacking these es- 
sential elements yet bearing the partial organic potential often 
found in failures of fertilization, they suggest it may be possi- 
ble to procure embryonic stem cells without producing an or- 
ganismal or embryonic entity that can meaningfully be desig- 
nated a being with moral standing. 
Proponents argue that there is a natural biological prece- 
dent for such an entity lacking the qualities and characteristics 
of an organism yet capable of generating cells with the charac- 
ter of embryonic stem cells. Teratomas are germ cell tumors 
that generate all three germ layers as well as more advanced 
cells, tissues, and partial limb and organ primordia. Yet these 
chaotic, disorganized, and nonfunctional masses lack entirely 
the structure and dynamic character of an organism. Likewise, 
failures of fertilization due to abnormal complements or chro- 
matin configurations (imprinting) of the chromosomes may still 
proceed along partial trajectories of organic growth without 
being meaningfully designated as organismal entities. 
These natural examples of “partial generative potential” 
(described by some as ‘pseudo-embryos'), together with other 
observations of early embryonic process, have led to a diverse 
array of suggestions for ways that embryonic stem cells may 
be produced without raising the moral issues involved in the 
creation and destruction of human embryos. These sugges- 
tions include the use of aneuploidies, polyploidies, viable cells 
from embryos in arrested development, parthenotes, and chi- 
meras of human nuclear material and animal oocytes. Each 
presents its own particular technical challenges and raises 
unique and unfamiliar moral considerations. The scientific 
prospects for such projects remain largely unexplored in hu- 
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