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Name: Asher
Status: Student
Grade:  9-12
Location: N/A
Country: United States
Date: May 2007

I would like to know if it were at all possible to create a human/animal chimera?

Early embryos can fuse to develop into a single organism. If this happens, the resulting organism, known as a chimera, will have some cells from one embryo and some cells from the other embryo. The most famous example of this is the "geep" which is the resulting organism from the fusion of goat and sheep embryos and has regions on its skin with sheep wool and regions with goat hair. In humans, there have been cases where fetuses that would have normally developed into fraternal twins fuse to form one fetus, and in these cases the humans will be chimeras in that they have cells derived from two separate zygotes (fertilized egg cells).

While there are moral concerns with trying to create a human/animal chimera, a lab from University of Nevada, Reno actually created chimeric sheep with 15% human cells in the hopes of creating animals whose organs could be used for transplantation into humans. They did this by injecting human cells into developing sheep fetuses, and while the animals produced looked like a normal sheep, their organs contained human cells. While this is a far cry from a talking half-human sheep, these animals are human-animal chimeras.

Ethan Greenblatt
Ph.D. Candidate
Stanford Department of Chemistry

The case of the woman who is her own twin (Aired on Discovery Health) shows that she is apparently the result of the fusion of two fertilized eggs, one destined to be a female and the other a male (her fraternal twin brother). Many of the tissues in her body (blood, ovaries and cheek cells) carried the DNA of what would have been her fraternal twin brother. They eventually found "her" DNA in her thyroid cells which matched the DNA of her children. So chimeras apparently do ocur during embryonic development.

Ron Baker, Ph.D.

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