Word: embryos
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...Vitro Fertilization When Louise Brown was delivered in England on July 25, 1978, the test-tube-baby industry was born. Scientists had joined her parents' eggs and sperm in a Petri dish and then implanted the embryo in her mother's uterus. (Elizabeth Carr, above, was the U.S.'s first in vitro-fertilized baby.) Despite a dismal 15% success rate, the process remains the treatment of choice for infertile couples...
WHAT IT LED TO: Fertility drugs, fertility clinics, the 65-year-old mom, the McCaughey septuplets, egg donors, embryo rights, embryo custody battles...
...gene that helps shape the thorax of the body. The promoter is a 200-letter paragraph of DNA, and in the two species it differs by just a handful of letters. The effect is to alter the expression of the HoxC8 gene in the development of the chicken embryo. This means the chicken makes thoracic vertebrae in a different part of the body than the mouse. In the python, HoxC8 is expressed right from the head and goes on being expressed for most of the body. So pythons are one long thorax; they have ribs all down the body...
...also uplifting, for it reminds us more forcefully than ever of a simple truth that is all too often forgotten: bodies are not made, they grow. The genome is not a blueprint for constructing a body. It is a recipe for baking a body. You could say the chicken embryo is marinated for a shorter time in the HoxC8 sauce than the mouse embryo is. Likewise, the development of a certain human behavior takes a certain time and occurs in a certain order, just as the cooking of a perfect souffle requires not just the right ingredients but also...
...bundle of squealing ethical questions and implications for the future of the species. After hundreds of tries, Lesley Brown's doctors found the secret to creating a baby outside the womb: having fertilized her egg in vitro, or in a Petri dish, they implanted the embryo after only 2 1/2 days rather than waiting for five and were rewarded with their first successful pregnancy. The breakthrough was not chronicled in some journal of reproductive medicine. The whole world awaited the birth because at the suggestion of one of their doctors, the parents had negotiated exclusive rights to the first baby...