clonned sheep

1. DOLLY
Dolly, female Finn Dorset sheep that lived from 1996 to 2003 was the first clone of an adult mammal,
produced by British developmental biologist Ian Wilmut and colleagues of the Roslin Institute, near
Edinburgh, Scotland. The announcement in February 1997 of Dolly’s birth marked a milestone in
science. Dolly wasn’t the first animal to be cloned ,research on cloning had been going on since the
mid-20th century but she was the first example of successful cloning of a mammal from an adult cell,
rather than a more malleable embryo.
Dolly was cloned from a cell taken from the mammary gland of a six-year-
old Finn Dorset sheep and an egg cell taken from a Scottish Blackface
sheep & was born to her Scottish Blackface surrogate mother on 5th July
1996 ,means Dolly had three mothers : one provided the egg, another the
DNA, and a third carried the cloned embryo . Dolly’s white face was one of
the first signs that she was a clone because if she was genetically related
to herc surrogate mother, she would had a black face.
She was created using the technique of somatic cell nuclear transfer, where the cell nucleus
from an adult cell is transferred into an unfertilized oocyte (developing egg cell) whose cell nucleus
had already removed. The hybrid cell is then stimulated to divide by an electric shock, and when it
develops into a blastocyst it is implanted in a surrogate mother. The production of Dolly showed that
genes in the nucleus of such a mature differentiated somatic cell are still capable of reverting to an
embryonic totipotent state, creating a cell that can be developed into any part of an animal. The
reconstructed embryos were transferred to surrogate Scottish Blackface ewes. Out of 13 recipient
ewes, one became pregnant, and 148 days later, which is essentially normal gestation for a sheep,
Dolly was born.
Dolly gave birth to six lambs in total. Her first lamb, named Bonnie, was born in April 1998. The next
year Dolly produced twin lambs Sally and Rosie, and she gave birth to triplets Lucy, Darcy and Cotton
in 2000.
In late 2001, at the age of four, Dolly developed arthritis and began to walk stiffly and was successfully
treated with anti-inflammatory medication, although the cause of the arthritis was never discovered.
Dolly continued to have a normal quality of life until February 2003, when she developed a cough. A
CT scan showed tumours growing in her lungs and the decision was made to euthanise Dolly rather
than risk her suffering. Dolly was put to sleep on 14th February 2003, at the age of six and half year.
The Roslin Institute gifted Dolly’s body to the National Museum of Scotland in Edinburgh, where
she has become one of the museum’s most popular exhibits and is currently on display in the Animal
Word galleries.