Dolly the Sheep (1996-2003) was the first mammal to be born as the result of cloning from adult cells.

Dolly was born on the 5th of July, 1996, but, perhaps because of the controversy surrounding cloning, her birth was not publicised until the following year.

The birth followed from earlier advances made by the same team at the Roslin Institute in Edinburgh. Dolly's predecessors were Megan the Sheep and Morag the Sheep, born about a year earlier, but cloned from embryonic cells. The techniques used in manipulating the cells included the use of microscopic needles invented for human fertility treatments in the 1970s. It is worth noting that 276 unsuccessful attempts were made before Dolly was created.

It went like this:-

  • The nucleus was removed from a Scottish Blackface oocyte cell.
  • The nucleus from a Finn Dorset mammary cell was inserted. Selection of this cell was novel- it was a quiescent cell meaning that it had stopped dividing.
  • The resulting cell was "zapped" with an electric current to fuse its new constituent parts together.
  • It was then placed in the reproductive system of a Scottish Blackface ewe.

Dolly was therefore born a purebred Finn Dorset, but from a Scottish Blackface. This was a simple way of proving that she really was a clone, rather than the result of conventional breeding.

Dolly gave birth to 4 lambs in 1998 and 1999, after mating in the usual manner- this was considered an important sign that Dolly was a fully successful clone.

Dolly was put down on February 14, 2003, after suffering from progressive lung disease. Although sheep often live for 10-12 years, lung diseases are not uncommon, especially among sheep that are kept indoors. So is not clear if this illness was a result of her unusual conception. Studies had shown that the telomeres in her cells were shorter than those of a normal sheep of that age- a sign that Dolly was in some ways old beyond her years. Dolly was cloned from cells taken from an adult (6 year old) sheep. It was almost as though she started life with the cells of an adult.

Her autopsy showed that she also suffered from arthritis- this is more likely to be a sign that cloning, at least using 1996 methods, has inherent technical problems.

Pub quiz aficionados will already be aware that Dolly was cloned from mammary cells, and was hence named after Dolly Parton.

And the final resting place for this scientific landmark? Dolly has been preserved and is on display at the Royal Museum in Edinburgh.


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