The drug works by using high doses of the female hormone progestin, which also is contained in birth-control pills, to block a potentially fertilized egg from becoming implanted in a woman's uterus.

WSJ: Judge Eases Restrictions on Plan B Emergency Contraceptive

The adult cell whose nucleus was transferred into the egg that became Dolly had a male imprinted genome that was inherited at birth and copied to every cell of the donor's body.

ECONOMIST: A ��virgin birth�� in mice

The drug works by using high doses of the female hormone progestin, which also is contained in birth-control pills, to prevent ovulation or block a potentially fertilized egg from becoming implanted in a woman's uterus, according to the drug's label.

WSJ: Judge Eases Restrictions on Plan B Emergency Contraceptive

The government is therefore interested in discovering more about the beasts, so as not to kill the shark that lays the golden egg (though one recent finding is that whale sharks, unlike many of their relatives, actually give birth to live young, rather than laying eggs).

ECONOMIST: Whale sharks