Word: eggs
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Dates: during 1970-1979
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FMCA is not for vanners, camper-trailer haulers or owners of the cruder class of recreational vehicles. The distinction is not so much an economic or social delineation as a statement: the esteemed "goose egg" FMCA plaque on the front of a vehicle, be it a mansion of the macadam or a turnpike retirement pad, means that it is a livable, functioning home. Its owner belongs to what may be the largest extended family in America...
Finally, last Nov. 10, Steptoe extracted an egg from one of Lesley's ovaries, and placed it in a laboratory dish. Edwards then fertilized the egg with John Brown's sperm. Two and a half to three days later, when the egg had undergone three cell divisions, it was placed in Lesley's uterus. Said Edwards about Baby Louise: "The last time I saw her, she was a beautiful eight-celled embryo...
Unlike in vitro fertilization, which lets nature take its course (sperm from the father and an egg from the mother unite, albeit in a test tube), cloning is asexual, single-parent reproduction. Instead of being a mixture of genes from two parents, the clone (from the Greek word klon, meaning twig or slip) is a genetic copy of its single parent...
...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 of unfertilized egg cells from female frogs. These nuclei were then replaced with nuclei taken from the cells of developing frog embryos, which at this early stage were merely clumps of cells that had not yet differentiated into specific organs. Some of the frog eggs, with their newly implanted nuclei, acted...
Though cloning mammals by the classic method is a long way off, scientists are moving closer to cloning mice by an indirect route. In this technique, devised by 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...