To assure that the fusion was successful, the cells had to have coordinated cycles of DNA duplication and RNA production. This measure was taken to insure that the eggs would grow together once they were placed into the uterus of the surrogate mother. Clones have also resulted from far more differentiated cells. For example, clones were created from the udder of a pregnant ewe, whose mammary cells were growing at a vigorous rate. These cultured fibroblasts not only reproduced at a desirable rate, but they also had stable chromosomes.
Clones are a result of the union of a donor cell, a recipient cell and a surrogate mother.
The appearance of the offspring resembles the donor, in this case the offspring resembled that particular breed of sheep. The appearance is the result of the genetic information that was part of the donor cells nucleus. The genetic information that contributes to inherited appearance is found on chromosomes in the nucleus. On these chromosomes there are special genes for the inheritance of certain traits. It is these genes that give rise to an offspring that resembles the appearance of the donor sheep.