Реферат: Sex Preselection Essay Research Paper Sex Preselection
Sex Preselection Essay, Research Paper
For many years, mankind has wondered how to choose the sex of a child before its birth for which countless myths, folk remedies, and magic potions have been offered as a solution. None of these methods were based on scientific evidence. However, in recent years gender selection has been made possible through advances such as preimplantation genetic diagnosis using biopsy methods combined with in vitro fertilization and sperm separation using flow cytometry techniques (Reubinoff, 1996, p. 344). These methods can increase the likelihood of producing a child of the desired sex, although none can guarantee success. The fact that the procedure can be fairly simple and inexpensive may cause medical practices to notice an increase in the demand for the services. This will most likely bring about many ethical and moral dilemmas as is often accompanied by scientific progress in modern society.
Preimplantation genetic diagnosis is a technique that can be used during in vitro fertilization to test embryos for genetic disorders as well as the sex by observing chromosome content. In this procedure, a woman uses fertility drugs so that she releases several eggs in one cycle. The eggs are taken from the mother, fertilized, and then allowed to divide. After two or three days, one or two cells are removed from the embryo and tested (Verlinsky, 1996, p. 359). The current primary means of testing the embryos is fluorescent in situ hybridization. This method is based on the labeling of specific DNA sequences of X and Y-chromosomes. It illuminates the X and Y-chromosomes in different colors, therefore providing a means of separating the male and female embryos. This technique is also useful in that it can detect chromosomal abnormalities such as XO and XXX. Furthermore, the procedure?s staining methods can allow accurate sex determination within two hours. Although it has been argued that the FISH technique is acceptable when the embryo is homogenous, but remains questionable when it is heterogenous (Coonen, 1996, p.134).
Another technique used in sex preselection is called MicroSort. ?Utilizing new flow cytometric separation technology, the X or Y chromosome ?bearing sperm can be sorted and the enriched fraction of sorted sperm can be used for medical insemination (intrauterine insemination), in vitro fertilization, or intracytoplasmic sperm injection.? (Genetics & IVF Institute, 1998) Normally, semen specimens contain an equal amount of X- and Y-bearing sperm. If either of the two can be increased, so can the chances of conceiving a child of that sex. This method is currently somewhat more successful for parents choosing to have a girl. It is expected to be five to six times more likely to have a female child, while on the other hand, the chances of a boy are only increased to 2: 1. Obviously, this does not result in the complete elimination of either X or Y chromosome ?bearing sperm in the final sperm preparation. This sorting technique has resulted in over four hundred offspring of various species as well as the recent births in humans. (Genetics & IVF Institute, 1998). The first people to use this technique were looking to avoid a deadly disease called hydrocephalus, which almost always effects boys. A healthy baby girl was born to the couple in August of 1996. As of April of 1998 eleven healthy babies have been born after using this procedure (Genetics & IVF Institute, 1998).
Gametrics (also called the Ericsson method for its inventor) is a rather new technique that is used in conjunction with artificial insemination. The sperm is placed in a vertical glass tube that contains a solution that is used to slow its movement. The male sperm will swim down faster and the female sperm will remain at the top. The sperm of the desired gender can then be collected and used with artificial insemination. This method is about seventy-five to eighty percent effective in achieving the desired sex. It is available at thirty-three clinics throughout the United States. The cost is between six hundred and one thousand dollars per treatment (Russell, 1998, p. 112).
There are several reasons why parents would want to choose the sex of their child. Perhaps the most important would be for the prevention of passing on sex-liked diseases such as Hemophilia. Since this disease almost always affects boys, it would be in the parents? best interest to produce offspring that are female if either parent carries that sex-linked gene. Another reason for sex preselection might be for what is often called ?family balancing? (Schrof, 1998, p. 68). This term refers to wanting girls and boys in the family. For instance, if a couple has two boys and they want the next child to be a girl, a method of gender preselection would help their odds of having a girl. This could help to limit the size of families where the parents may continue having babies until they get the son or daughter that is missing. A third incentive for choosing one of these methods is where there would be a preference of one sex to the other. A good example of this can be seen in China and India, where the desired gender is almost always male. Gender selection in these countries could be a far better alternative to the practices seen there. Routine abortions of female fetuses in India and other parts of Asia are very common as well as ?dying rooms? in China where baby girls are said to be abandoned (Lemonick, 1998, p. 68). These practices will, however, enable people to act upon their biases of one sex or the other. These societies are already out of balance and this could make the problem even worse. Such an outcome as this is highly unlikely in the United States, where surveys show that most families desire an equal number of boys and girls. The same polls indicate that Americans believe the ideal family has a male as the first child. First children are often more dominant and assertive and the same is generally true for male offspring. ?Skewing the population toward doubly dominant firstborns could make it even harder to rid society of gender-role stereotypes.? (Lemonick, 1999, p. 65)
Reproductive technology is moving forward at an astonishing rate. Researchers are finishing up sex-selection devices that may be available over the counter within the next few years. Also, ?scientists are now discussing germ-cell genetic engineering, another controversial new technique by which couples tinker with their own DNA to give birth to kids of a preferred height, physique, hair color, IQ, or even temperament (Schrof, 1998, p. 68).? If gene therapy lives up to its promise, parents will someday be able to go even further that weeding out undesirable traits and be able to insert genes that have been produced in a laboratory. The genes responsible for our physical and mental characteristics have not been identified yet. At the present time, the only traits that can be identified besides gender are about one dozen serious genetic diseases. This type of gene therapy is at least several years away (Lemonick, 1999, p. 64).
Gender preselection can be very advantageous as well as controversial. It is beneficial to determine the sex of a fetus in order to assess the possibility of disease and can aid with family balancing. Some ethicists are concerned that choosing more of a certain sex could cause drastic changes in the population. ?Confusion and uncertainty still exist regarding the clinical efficiency of in vivo clinical manipulation methods and various sperm separation techniques because of lack of well-designed prospective controlled clinical trials.? (Reubinoff, 1996, p. 343)
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