 This animation outlines the process the Roslin Institute scientists followed to create Dolly, the world's first mammal to be cloned from cells taken from an adult Dorset U. To help you follow the process we have labelled the parent sheep, sheep 1 and sheep 2. Note that sheep 1, the U to be cloned, has a white face, a fact that was used to help check that cloning was successful. The first step involved taking cells from the udder of sheep 1 and culturing them in a gel to create a batch of identical cells. In the course of culturing these cells they were deliberately deprogrammed to let these cells regain their potential to become totipotent to form any cell needed in the future clone and not simply another cell from a used udder. This single achievement marked a significant breakthrough. Meanwhile an egg or ovum was removed from sheep 2, a black faced female Scottish U, to be prepared for implantation. Using techniques developed in human fertilization treatments conducted at a microscopic level, the nucleus from the sheep 2's ovum was removed or inucleated to make sure that none of sheep 2's DNA and genotype could be passed on to the next generation. Once the ovum had been inucleated it was then fused with a cell from the sheep 1 culture of deprogrammed udder cells. In effect emulating the process of a sperm entering the egg but with both copies of the chromosomes coming from the same parent sheep sheep 1, so the newly fertilized egg is genetically identical with this single parent. Once fusion had taken place chemical factors in the egg are released to stimulate cell division. Once the cells had multiplied sufficiently to form the makings of an embryo, the new cell cluster was transplanted into the womb of a third sheep which we will call sheep 3 for a 21 week gestation period. In total 277 attempts were made to fuse the adult cells with a nucleated eggs, only one survived. Dolly was born on the 5th of July 1996 by Caesarean section and was found to be genetically identical to sheep 1 from whose udder her DNA originated. Dolly lived until the 14th of February 2003 when she was put down suffering from a progressive lung disease.