Scientists take an ovum from a female of the species they're cloning and remove all the DNA from inside.
科学家从他们正在克隆的物种的雌性身上取出一个卵子,并从里面去除所有的 DNA。
英语百科
Egg cell
The egg cell, or ovum, is the female reproductive cell (gamete) in oogamous organisms. The egg cell is typically not capable of active movement, and it is much larger (visible to the naked eye) than the motile sperm cells. When egg and sperm fuse, a diploid cell (the zygote) is formed, which gradually grows into a new organism.