Dolly, the cloned sheep

Scientists Keith Campbell and Ian Wilmut of the Roslin Institute of Edinburgh managed to successfully clone the first mammal, Dolly the sheep (July 5, 1996 - February 14, 2003) from an adult cell.

The process was as follows:

1. Were taken by biopsy, epidermal cells of the mammary gland of an adult sheep and cultured in a nutrient medium. Was gradually decreasing the protein concentration of the medium to stop cell division in culture and leave them at rest.
2. In parallel, another sheep was subjected to hormone treatments to achieve multiple ovulation. Several of the oocytes produced by the sheep were enucleated, ie the nucleus was extracted by suction through a specimen.
3. They contacted the cultured cells grown in enucleated oocyte resting and subjecting them to a brief electrical pulse to create micriporos in the membranes of both cells, emulating the acrosome reaction, and thus favor the merger and to open calcium channels, causing a reaction similar to that which causes the formation of the fertilization membrane.
4. Once achieved the fusion of enucleated oocyte with the nucleus from an adult cell, was obtained equivalent to a diploid cell zygote after the union of oocyte and sperm. This "zygote", with the same genetic makeup as the nucleus of the mammary gland of the sheep and the cytoplasm of the oocyte, was implanted and gestated in the uterus of a third sheep.
5. The result was the birth, 148 days after the sheep Dolly, genetically identical to the sheep whose mammary gland cells were extracted.

Reproductive cloning has been successfully tested in various mammals. An interesting application field is the cloning of animals in imminent danger of extinction.