CLONING MAMMALS: WHAT DOES IT MEAN (an opinion from Scott Gilbert) I. Dolly the sheep Individuals from two mammalian species--sheep and cows--have recently been cloned.The sheep Dolly has been generated asexually by fusing the nucleus of an adult mammary gland cell to an enucleated sheep egg (Wilmut et al., 1997). What does this mean Scientifically, Dolly has not told us much. The cloning of an ...