Hans Spemann
Walter Sutton
Oswald Avery
Francis Crick
James Watson
Paul Berg
Stanley Cohen
Herbert Boyer
Kary B. Mullis
Steen Willadsen
Ian Wilmut
Keith Campbell
Richard Seed

Danish scientist who made great contributions to reproductive physiology and embryology. In 1984 he created the first cloned farm animal using the method of nuclear transfer.

Willadsen, born in Copenhagen, Denmark, attended the Royal Veterinary College of Copenhagen. A few years after graduating, he became bored in the veterinary field and returned again to the Royal Veterinary College to obtain a degree in reproductive physiology.

Willadsen, at the British Agricultural Research Council's Unit on Reproductive Physiology and Biochemistry, successfully developed a process for efficiently freezing, storing, and then thawing livestock embryos.

Willadsen then attempted to divide the single celled embryo of a sheep, mimicking Hans Spemann's work with frogs in 1902. He could divide the embryos, but when the individual cells were placed in sheep oviducts to grow, the original embryo division caused the cells to die. Willadsen discovered that a substance called agar could protect the embryos, and was able to succeed in completing the experiment. Willadsen's discovery of the agar coating technique allowed scientists to perform new types of experiments, because embryos could now be manipulated in drastic ways with the worry of damaging the embryo. Both this technique, and his embryo freezing research proved to be instrumental in Willadsen's later successful cloning experiments.

Next in the line of Willadsen's work was the production of Chimeras. During an organism's early stages of embryonic development, Willadsen combined the cells of different embryos, creating Chimeras. The technique worked, and Willasden created abnormal animals that merged characteristics of sheep and goats, as well as sheep and cows. Willadsen wanted his work to be used to increase the populations of endangered species by having closely related common animals serve as surrogate mothers in the births of endangered organisms.

Still working for the British Agricultural Research Council, Willadsen, in 1984, used the nuclear transfer method to produce the first cloned farm animal, a sheep, from embryo cells. Following this success, Willadsen joined Grenada genetics in 1985, and used his technique to clone cattle embryos. At Grenada genetics Willadsen conducted an unpublished experiment in which he cloned a cow from a differentiated one-week-old embryo cell. Willadsen is highly optimistic about the future of cloning. He has stated his belief that it will be long long at all before someone will take the next step to clone a human.

"The role of the scientist is to break the laws of nature, rather to establish, let alone accept them."

- Steen Willadsen

 

Timeline: Willadsen clones first farm animal.
Timeline: Clones From Differentiated Cells
Timeline: Willadsen Joins Grenada

(Willadsen quote from the book Clone, by Gina Kolata.)

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