Chimera Formation (Animal and Human)

A CHIMERA IS an organism that is made up of more than one genetically distinct type of cell. Chimeras can either form naturally or be artificially produced in the laboratory by three mechanisms: mixing stem cells from two different individuals, introducing stem cells into a fully developed tissue, or combining two fully developed tissues into one organism. Scientists study chimeras to answer fundamental questions about stem cell biology, organ transplant biology, embryonic development, human diseases, and genetics, as well as to [Page 96]test drug effectiveness. Although many types of chimeras are possible, the formation of human—only, animal—only, and human—animal chimeras is described here.