There are several advantages in using adult body cells: cultures are easier to obtain and maintain; also, there is greater scope for genetically engineering such cells and screening them to select successfully modified cells. Nuclear transfer, using embryo cells or body cells, is now used increasingly to replicate elite animals in the livestock industry, to produce genetically engineered mammals for commercial use (e.g. goats that secrete human proteins in their milk), and to replicate endangered species. However, the failure rate is generally high, and even the few live clones produced often have congenital defects that shorten their lives. This shows that ‘reprogramming’ differentiated body cells poses formidable technical obstacles.
"nuclear transfer." A Dictionary of Biology. . Encyclopedia.com. (September 20, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/nuclear-transfer
"nuclear transfer." A Dictionary of Biology. . Retrieved September 20, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/nuclear-transfer