They're called "chimeras," human-animal hybrid embryos created in a laboratory. Britain will soon introduce a law allowing the creation of chimera with certain safeguards. One is a requirement that they be destroyed within two weeks of creation. Another is a prohibition on implanting chimera into a woman's body.
Britain's Roman Catholic Bishops are crying foul (or "fowl" perhaps) and have filed a submission arguing that the genetic mothers (egg donors) of chimera should have the right to raise them if they wish.
Chimera are created by injecting animal DNA into human embryos or vice versa. One purpose for the research is to determine if such creatures could be used to grow human tissue, perhaps even organs.
In their submission to the committee, they said: “At the very least, embryos with a preponderance of human genes should be assumed to be embryonic human beings, and should be treated accordingly.
“In particular, it should not be a crime to transfer them, or other human embryos, to the body of the woman providing the ovum, in cases where a human ovum has been used to create them.
“Such a woman is the genetic mother, or partial mother, of the embryo; should she have a change of heart and wish to carry her child to term, she should not be prevented from doing so.”