How They Cloned a Sheep

udder cells

1. Scientists took udder cells from Dolly’s DNA mother. They let the cells multiply and then they stopped the process when they had divided enough.

egg cells

2. They took an egg cell from a different sheep and removed the nucleus.

udder cell joins to cell without nucleus using electricity

3. They put one udder cell next to the egg cell without a nucleus and joined them using electricity. The egg cell now contained all the udder cell’s DNA.

cells grow into an embryo

4. The egg cell divided until it developed into an embryo. An embryo is the early stage of an animal before it has been born or hatched. This embryo was placed inside a third sheep. Five months later, this sheep gave birth to Dolly.

Image Credits:

Photos: Dr. Ian Wilmut and Dolly; Dolly and her birth mother, courtesy of the Roslin Institute; Illustrations: Clay Meyer