Word: either
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Dates: during 1970-1979
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Lester Brown, the president of Worldwatch Institute, a Washington-based environmental research group, believes that the world's life-supporting resources, notably soil, grasslands, forest and fish, are either deteriorating or being depleted, and that these factors inevitably will lead to less growth and more inflation...
...that precious pregnancy turns out will shortly be known; one estimated due date is Aug. 4, but a swing of two weeks on either side is perfectly normal. Steptoe and Edwards, for their part, must surely feel highly confident; otherwise these experienced researchers would never have allowed the pregnancy to go so far. Yet on the eve of what may well be the most awaited birth in perhaps 2,000 years, there are also still many unanswered questions. For the Brown family, it is whether their test-tube child is healthy and can ever hope to have anything resembling...
...puberty, eggs are released, usually one at a time, about midway in the menstrual cycle. The process is intricate and marvelous. Stimulated by hormones, part of the body's chemical signaling system, a ripe egg is expelled from its grapelike encasement, or follicle, in the ovary; in any month, either of the female's two ovaries may contribute an ovum. Then the egg enters the nearby fallopian tube. If coitus has taken place, the egg will shortly run into a swarm of tailed sperm that have managed, like salmon battling upstream, to fight their way into this passageway...
...Yale Biologist Clement Markert, eggs are removed from a female mouse shortly after fertilization. At this early stage, genetic material from egg and sperm have not yet mixed; the mother's and father's genes are still in two distinct sacs, called pronuclei. Using microsurgery, Markert removes either pronucleus. The egg is then exposed to a chemical that causes the remaining pronucleus to replicate, thus giving the cell a full complement of genes. Then the cell itself divides, and the resulting embryo is placed in the uterus of a female mouse to develop. Using this technique, Biologist Peter...
...problems. Says Nobel Laureate James Watson, co-discoverer of DNA's double-helix structure: "What's to be gained? A carbon copy of yourself? Oh, if the Shah of Iran wanted to spend his oil millions on cloning himself, that's fine with me. But if either of my young sons wanted to become a scientist, I would suggest he stay away from research in cloning humans. There's no future...