A clinician prepares cells for in vitro fertilization, or IVF, the treatment for infertility. In the future, it could be joined by IVG, in vitro gametogenesis, a new process that could turn any cell first into a stem cell and then into a sperm or egg cell. Lluis Gene/AFP via Getty Images hide caption
Barbra Streisand, on stage with her dog, Samantha, who was cloned to create Miss Violet and Miss Scarlett. KMazur/WireImage hide caption
Barbra Streisand plays with her dog Samantha near her son, Jason Gould (left), and husband, James Brolin, in Paris in 2007. Samantha died last year, but Streisand now has clones of the dog. Philippe Wojazer/Reuters hide caption
A surgical team at Sooam Biotech in Seoul, South Korea, injects cloned embryos into the uterus of an anesthetized dog. Rob Stein/NPR hide caption
Ken (left) and Henry were created using DNA plucked from a skin cell of Melvin, the beloved pet of Paula and Phillip Dupont of Lafayette, La. Edmund D. Fountain for NPR hide caption
Mammoths had a distinctive version of a gene known to play a role in sensing outside temperature, moderating the biology of fat and regulating hair growth. That bit of DNA likely helped mammoths thrive in cold weather, scientists say. Courtesy of Giant Screen Films, 2012 D3D Ice Age, LLC/Penn State University hide caption
A woolly mammoth skeleton gets auctioned off in Billingshurst, England. Peter Macdiarmid/Getty Images hide caption
This mouse egg (top) is being injected with genetic material from an adult cell to ultimately create an embryo — and, eventually, embryonic stem cells. The process has been difficult to do with human cells. James King-Holmes/Science Source hide caption
A file photo from 2011 shows a man touching a giant bronze sculpture of a mammoth in the Siberian city of Khanty-Mansiysk. A team of Russian and South Korean scientists who found a well-preserved frozen woolly mammoth carcass this month say it also included blood. Natalia Kolesnikova/AFP/Getty Images hide caption
Human embryos grow in a petri dish two days after scientists in Oregon cloned them from a donor's skin cell. http://www.flickr.com/photos/ohsunews/8726915230/in/photostream//Courtesy of OHSU Photos hide caption