The history of Cloning

Sea Urchin Cloned

May 4, 1885

The sea urchin is a relatively simple organism that is useful for studying development. Dreisch showed that by merely shaking two-celled sea urchin embryos, it was possible to separate the cells. Once separated, each cell grew into a complete sea urchin.

Artificial embryo twinning in a vertebrate

Apr 30, 1902

Spemann’s first challenge was to figure out how to split the two cells of an embryo much stickier than sea urchin cells. Spemann fashioned a tiny noose from a strand of baby hair and tightened it between two cells of a salamander embryo until they separated. Each cell grew into an adult salamander. Spemann also tried to divide more advanced salamander embryos using this method, but he found that cells from these embryos weren’t as successful at developing into adult salamanders.

First successful nuclear transfer

Jun 26, 1952

Briggs and King transferred the nucleus from an early tadpole embryo into an enucleated frog egg (a frog egg from which the nucleus had been removed). The resulting cell developed into a tadpole.

Nuclear transfer from a differentiated cell

Jun 27, 1958

Gurdon transplanted the nucleus of a tadpole intestinal cell into an enucleated frog egg. In this way, he created tadpoles that were genetically identical to the one from which the intestinal cell was taken.

First mammalian embryo created by nuclear transfer

Apr 27, 1975

Mammalian egg cells are much smaller than those of frogs or salamanders, so they are harder to manipulate. Using a glass pipette as a tiny straw, Bromhall transferred the nucleus from a rabbit embryo cell into an enucleated rabbit egg cell. He considered the procedure a success when a morula, or advanced embryo, developed after a couple of days.

First mammal created by nuclear transfer

Sep 4, 1984

Willadsen used a chemical process to separated one cell from an 8-cell lamb embryo. The he used a small electrical shock to fuse it to an enucleated egg cell. As luck would have it, the new cell started dividing.

Nuclear transfer from embryonic cell

May 28, 1987

Using methods very similar to those used by Willadsen on sheep, First, Prather, and Eyestone produced two cloned calves. Their names were Fusion and Copy.

Nuclear transfer from laboratory cells

Jan 1, 1996

All previous cloning experiments used donor nuclei from cells in early embryos. In this experiment, the donor nuclei came from a slightly different source: cultured sheep cells, which were kept alive in the laboratory.

Dolly the Sheep

Jul 5, 1996

How she was createdDolly the sheep was the first mammal to have been successfully cloned from an adult cell. She was cloned at the Roslin Institute in Midlothian, Scotland, and lived there until her death when she was six years old. Her birth was announced on February 22, 1997.

First primate created by embryonic cell nuclear transfer

Mar 25, 1997

Primates are good models for studying human disorders. Cloning identical primates would decrease the genetic variation of research animals, and therefore the number of animals need in research studies.

More mammals cloned by somatic cell nuclear transfer

Mar 25, 1999

After the successes leading up to Dolly and Polly, other scientists wanted to see if similar techniques could be used to clone other mammalian species. Before long, several more animals had been successfully cloned. Among them were transgenic animals, clones made from fetal and adult cells, and a male mouse; all previous clones had been female.