Word: embryos
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...hope can be traced to the birth of Louise Brown in England in 1978. Louise was the world's first test-tube baby, conceived by means of in vitro fertilization, in which, after her mother's egg and father's sperm were united in a laboratory, the resulting embryo was implanted in her mother's womb. Louise's subsequent, internationally celebrated birth launched a new branch of medicine that has come to be known as "assisted reproductive technology...
...sense, the furor was an artificial one. Embryos of this sort are routinely destroyed in small batches every week, as they have been since the 1980s. The term embryo, moreover, carries an emotional charge that may be misleading. These entities consist of a handful of cells, the very earliest stages of the nine-month process that turns a fertilized egg into a full-term baby. They were frozen only a few days at most after conception; they would not even merit the designation fetus until after three months in the womb. "You can't regard these as little people," says...
...other natural hormones. They know that these hormones are crucial to the development of a normal reproductive system. And they know that--in lab tests on animals, at least--vanishingly small amounts of industrial chemicals, delivered at just the crucial stage of fetal development, can "feminize" a male embryo, producing smaller testicles, low sperm output and a miniaturized or missing penis...
...fetus itself should not be considered human. Just because an embryo has the potential for life if it is allowed to grow inside the mother's womb doesn't mean that it has life or even a self. The fetus, in fact, does not and should not even have any legal rights apart from the mother until it has reached a state of viability, defined by the Supreme Court in Roe v Wade as the ability of the fetus to survive on its own or with the aid of machinery if extracted from the womb. It is true, though, that...
...could the brain and the body become so mismatched? Several explanations are possible. One is rooted in the process by which embyros take on sex differences. All human embryos develop in the very earliest stages of gestation along more or less feminine lines. Those destined to become males differentiate from the master template after a complex series of hormonal secretions starts to masculinize the embryo. Miscues in this process could result in crossed signals in the portions of the brain that are responsible for gender identity. That would help explain why there are more male-to-female transsexuals than female...