Experiments in the late nineteenth century on frogs provided the groundwork for cloning (McKinnell 9-10).

The method used a decade ago for the successful nuclear transplantation in amphibians required that the egg be enucleated, which meant removing the maternal hereditary material contained in the egg nucleus. Other hereditary material contained in the nucleus from a body cell would then be placed in the enucleated egg, and the resulting clone would be parentless:

Biologically, a mother is a mother by virtue of the fact that she contributes hereditary material via the chromosomes of an egg. . . A father is a biological father by virtue of the fact that he has contributed hereditary material via his sperm. Since no sperm has participated in the development of the cloned individual, there is no male parent (McKinnell 10-11).

Cloning higher animals has proven to be difficult, but scientists have persevered and have produced...
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