Word: sperm
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Novel approaches to babymaking seem to be coming at us so fast that we hardly have time to digest one before the next one hits--test-tube babies, egg donation, surrogacy, cloning and now sex selection. And just as with earlier methods, the new sperm-separation technique announced last week has triggered plenty of ethical concern. Only a few critics have argued that tampering with nature to avoid a sex-linked genetic disease should be taboo. But plenty have expressed misgivings about using the new technology more casually, to balance families, or simply because parents prefer boys or girls. Such...
These arguments are not very persuasive. In some developing countries where boys are more highly valued than girls, sex selection is already standard practice, accomplished by means of infanticide or amniocentesis and abortion. The new sperm-separation technique makes it easier for more people to practice sex selection in these countries...
...breakthrough is based on the long-known fact that sperm have a gender, in a manner of speaking: some carry an X chromosome and some carry a Y. If the former fertilizes an egg, the baby will be a girl; if the latter, a boy. Over the years, fertility gurus have tried to boost production of X- or Y-bearing sperm through diet, or attempted to pick out Ys by their supposedly faster swimming speed or distinct electric charge--with dubious success...
...beautifully simple idea. Since sperm bearing a Y chromosome (the one that creates little boys) contains nearly 3 percent less DNA than its female X chromosome counterpart, why not sort sperm by its genetic weight -- and stack the deck for couples who want to choose the sex of their child? Easier said than done, of course. But that's precisely the technique that a Fairfax, Va., fertility center is set to reveal Wednesday in the journal Human Reproduction. Based on the information released so far, this appears to be the most reliable gender-selection process ever developed...
...technique perfected by the not-for-profit Genetics & IVF Institute involves staining sperm cells with a DNA-sensitive fluorescent dye and then passing them single file through a laser beam. The cells are sorted based on the amount of light reflected by the fluorescent DNA. It's painstaking work -- sorting a single batch takes the better part of a day -- but the results speak for themselves: Of 14 pregnancies produced so far for couples who wanted a girl, 13 fetuses were female. Not entirely foolproof, but pretty close...