Cloning Amphibians

The first cloning of a vertebrate by nuclear transfer was reported by John Gurdon of the University of Cambridge in the 1950s. In nuclear plasmid a small ring of DNA found in many bacteria

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The process used to clone Dolly. Adapted from Gurdon, J. B., 1999.

Adult sheep

Mammary gland cells

Electrically induced fusion of mammary gland cell with enucleated egg cell

Mammary gland cell nucleus inside egg controls cell division

Adult sheep

Mammary gland cells

Electrically induced fusion of mammary gland cell with enucleated egg cell

Mammary gland cell nucleus inside egg controls cell division

Embryo culture

Embryo transfer to surrogate mother

transplantation, the nucleus of an unfertilized donor egg is either mechanically removed or it is destroyed by ultraviolet light in a process called enucleation. The original nucleus is then replaced by a nucleus containing a full set of genes that has been taken from a body cell of an organism. This procedure eliminates the need for the fertilization of an egg by a sperm.

The most successful nuclear transplants have been achieved after serially transferring donor intestinal nuclei, that is, putting an adult nucleus from an intestinal cell into an egg whose nucleus was destroyed, allowing the egg to divide only a certain number of times, removing nuclei from these cells, and repeating this process several times before allowing the embryo to complete development. Eventually, transplantation of nuclei from albino

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