Nuclear injection. To treat heritable emphysema, normal α 1-antitrypsin gene is cloned into a vector and transfected to sheep cells together with sheep promoter specific to mammary cells. The recombinant cells are injected into the nucleus of a sheep zygote with a micropipette.

The zygote is then transferred to the uterus of a surrogate ewe for development. When the transgenic sheep matures, it will produce milk containing functional human α 1-antitrypsin.