Advanced Cell Technology (ACT) used two different methods to try to create human embryos. The first one was akin to the standard approach used to clone sheep, cattle and monkeys. It involved taking the genetic material out of an unfertilised egg and replacing it with an adult cell. An ACT official says, "We scraped the DNA out of the egg cell and replaced it with DNA from the nucleus of the adult cell.' The researchers started with 19 eggs, adding skin cell genetic material to 11 and cumulus cell genetic material to the rest. Three of the eight eggs with cumulus cells divided once or twice before dying. It was impossible to retrieve stem cells. An embryo would have to grow for about five days and more important, from a ball of cells into a vesicle with two cell types.

The second method used by ACT was to stimulate an egg to divide without being fertilised. Any embryos that might result from this process, known as parthenogenesis, would have only the genes of the egg cell. But they cannot develop into babies.