Word: celling
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Dates: during 1970-1979
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...Moureu, 79, French scientist who in World War II helped to frustrate Nazi efforts to make an atom bomb and later saved Paris from rocketing; in Pau, France. Assigned in 1940 to guard France's secret reserve of deuterium oxide (heavy water), Moureu hid it in a prison cell, then smuggled it to England. In 1944, when the Germans unveiled V-2 rockets, Moureu calculated their size and working principles. He also helped pin point launching sites targeted on Paris, which were destroyed by U.S. bombers...
Under normal circumstances, pregnancy occurs when an ovum, or egg cell, released by a woman's ovary during ovulation is fertilized as it passes through the fallopian tube, successfully penetrated by just a single sperm that has traveled through the uterus. After the fertilized egg undergoes a number of cell divisions, the tiny clump of cells enters the uterus, where it burrows into the wall and develops for nine months or so until birth...
...come the inevitable countercurrent of doubt. Indeed as early as the 1940s, the eminent Boston gynecologist Dr. John Rock, a pioneer in development of the birth control pill, reported that he and colleagues had managed to fertilize an egg in vitro. But other scientists believe that the few cell divisions observed by Rock were nothing more than "parthenogenic cleavage" (division of the egg without the involvement of a sperm), probably induced by incidental stimulation of the ovum. Scientists were similarly skeptical of claims by Shettles in the 1950s that he had brought an externally fertilized human egg into the sixth...
Cloning is based on a remarkable fact. Virtually every cell in an organism -be the life form a human being, a maple tree or a bacterium-carries all the genetic information needed to create the whole organism. The reason that a liver cell is different from, say, a skin cell is that different genes in each cell seem to be "turned on." In the language of biologists, the cells are differentiated. U.S. Biologists Robert W. Briggs and Thomas J. King confirmed this principle and pioneered the basic technique of animal cloning in the early 1950s. They removed the nuclei...
...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 C. Hoppe of Jackson Laboratory in Bar Harbor, Me., and Swiss Microsurgeon Karl Illmensee have produced seven mice, all females...