An organism composed of two or more genetically distinct tissues, as an organism that is partly male and partly female, or an artificially produced individual having tissues of several species.external image geep.jpg

How Chimeras Are formed:

Chimeras are formed when two fertilized eggs or early embryos fuse together. Each different population of cells keeps its own characteristics, resulting in an animal with mixed and matched parts.


  • A "geep" (pictured) was produced in 1984 by combining sheep and goat cells
  • There have been rat/mouse chimeras, and human/rabbit embryos
  • Embryos that are created are usually not allowed to develop into fully grown animals
  • In August 2003, researchers in China fused human skin cells and rabbit eggs to produce stem cells.
  • In 2007, researchers in the US created a sheep with 15% human and 85% animal cells


  • Human skin cells can be combined with animal cells to produce stem cells
  • Animals with human organs can be given to humans if they need them
  • Allows us to learn about embryos and development
  • Can be used to study the effects diseases and treatments on humans

Legal Issues of Chimeras

Human Fertilization and Embryoloy Act (HEFA)

  • Created 1990
  • Formed in the UK
  • First legislation relating to chimeras, and other areas relating to bioethics
  • Allows only those with a bioethics license to perform embryonic testing
  • On May 18 Britain Legalized the creation of human-animal embryos

Other Countries Legal Issues With Chimeras

  • Many countries have banned the swapping of embryos
  • Other Countries such as Australia have recently legalized embryonic testing

American Laws on Chimeras

  • Few laws prohibiting chimeras
  • Only a few states have laws
  • Most beliefs are dependent on religion


To understand whether you think creating chimeras for human gain is morally right or wrong you must understand the pros and cons of the issue


  • Chimeras can be used to create organs for people who need a transplant
  • Some chimera’s have been used to understand the affects of diseases and medicines on humans
  • Chimera research is aiding in the understanding of human development
  • Does not require embryonic stem cells
  • Almost all of the uses of chimeras fall within the ethical guidelines that have been established


  • Chimera research goes against some religious beliefs
  • Some chimeras do not receive proper treatment
  • Researchers don’t generally allow the chimeras to fully develop

Study Questions-

There are many ethical issues surrounding the production and treatment of genetically produced chimeras, most of which even the scientists leading chimera research have not been able to fully answer. Some of these questions are:
  • How human should we make chimeras?
  • What rights do the animal-human chimeras have?
  • Should we be allowed to reconstruct genetic codes for our own benefit?
  • What harm can we be doing to the animals we are modifying?

Website Reviews:

Website URL:</span>

Name of Reviewer: Kevin Stetson

Date of Review: 5/20/08

Review of Site: (must cover all aspects of evaluation questionnaire)
The website was an article shown in Time magazine. The information is updated. The article is from 1984. The article holds no political or religious views, and it is more of a brief overview of how a geep, a type of chimera is formed. The purpose of the article is to inform the people chimeras and about how they are formed. I believe this website has many good articles on different topics, and I found the information easy to obtain and easy to understand.

Website URL:<span

Name of Reviewer: David Keim

Date of Review: 5/20/08

Review of Site: (must cover all aspects of evaluation questionnaire)
This website is run by the Chemie.DE Information Service. There is no date on the website. There are no biases, and the information is not an opinion. It is a brief overview, touching on the various types of chimeras. The website is intended to promote the Chemie.DE Information Service, and to sell laboratory equipment. Overall, I would recommend this website for those who want a brief overview of chimeras.

Website URL

Name of Reviewer: Sean

Date of Review: 5/19/08

Review of Site: This article appeared on It was last updated at 5:43 pm on April 29th 2005. The author maintains an unbiased viewpoint, simply trying to inform the reader. The article is a brief overview of how scientists are mixing human cells with animals to both study human development and provide vital organs to people in need.