XX embryos

Mr. P.F. Linehan plinehan at hgmp.mrc.ac.uk
Mon Jan 15 05:05:59 EST 1996

Sean Griffing wrote

"combining one human egg with another to create an XX embryo..... eggs that
abort themselves"

XX human embryos are created all the time - it's what happens when females
are conceived. What you are perhaps thinking of is experiments where 
the nuclei of gametes with parents of only one sex (either male or female) 
are fused and the resulting "egg" is implanted in a female and allowed to
develop. These eggs do not develop for very long since, in mammals, there
is a process of "imprinting" whereby some genes are differentially 
expressed depending on whether they have come from the father or the
mother. This seems to be an evolutionary adaptation to viviparity i.e.
giving birth to live young that are furthermore nourished by the mother
during the entire gestation period.

To my knowledge, work of this kind has not been done on humans but on
rabbits, mice and suchlike. I think that ethical committees would have 
big problems authorising such experiments on human embryos.

Hope this has been of help. If you want refs, email me.



pl1 at soton.ac.uk

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