Fertilized egg

Gregory Sullivan (sullivan@blaze.cs.jhu.edu)
Sun, 15 Mar 1998 08:24:37 -0500 (EST)

The issue of how fertilized human eggs should be treated was raised
recently on this list. There is an interesting paragraph about this topic
in a book review at the HMS Beagle web site. Below is the relevant
excerpt. Of course, there is still room for disagreement with the viewpoint


Remaking Eden Cloning and Beyond in a Brave New World
by Lee M. Silver
Avon Books, 1997

Begin excerpt from book review

By combining some underappreciated biology with common sense, he also
analyzes the assumptions underlying the claim that a fertilized human egg
deserves special status based on its potential for developing into a human
being. For example, the assertion that a unique genetic identity is created
at conception is undermined by the fact that the maternal and paternal
pronuclei don't fuse until the two-cell stage of development. Moreover, for
about two weeks after fertilization, each of the individual cells of the
embryo has the potential to give rise to a complete and distinct developing
embryo. Despite the acknowledged potency of each of these cells, their lost
potential is not mourned when one of them is plucked off from an early
embryo in order to carry out prenatal genetic diagnosis. Finally, since
cloning by nuclear transfer allows for the creation of a new embryo from
any somatic cell in the absence of conception, the act of conferring
respect or elevated status on biological potential is not supported, Silver
argues, by the modern facts of human reproduction.

end excerpt