GENETICALLY MODIFIED MICE
The science of biology has evolved to the point today that an animal's basic nature can be quickly and permanently changed by altering its generic structure. The possibilities that the genetic engineering of animals can bring us is endless; from the Harvard-Dupont mouse prone to developing cancer, to pigs with people-friendly organs that can be used for transplant purposes. But genetic engineering is, as yet, an imperfect science that yields imperfect results and too, endless risks. The use of humans for testing is far too hazardous for first-time products. Therefore, the use of animals, especially mice, as 'testers' is often seen as a way of helping our technological advances.There are two primary techniques that are utilized to modify an animal's genome (the unique combination of genes in an individual animal): Transgenesis by pronuclear microinjection and the manipulation of embryonic stem cells.Transgenesis by pronuclear microinjection is the process of permanently introducing a foreign gene into an animal, creating a transgenic animal that is genetically different from any other animal that ever existed. The following steps are taken to create a transgenic animal, the following steps are taken.
If this is the case, the mother is usually killed and the pups are removed and given to a foster mother to nurse and raise. The embryos are then transferred into the uterus of the foster mother with the hope that they will implant successfully and develop into healthy, genetically modified mouse pup. jected with a hormone to induce their ovaries to produce five-six times the number of egg cells that would normally be produced during ovulation, bred with a male mouse, and then killed so that the fertilized egg cells can be surgically removed. In some cases, the transgenes will become permanently inserted into the genetic make-up of the embryo. The same steps are then taken as the other method from here. Establishing the growth of these embryos in tissue culture requires the same steps as mentioned in the other method, but this technique involves growing the embryos in tissue culture. In order to receive these manipulated eggs successfully, the foster mother must be induced into a stage of false pregnancy, usually accomplished by breeding her with a vasectomized male mouse. They are exposed to specially constructed genes in a manner that permanently incorporated some of these genes into the genetic structure of the embryonic stem cells. Although it is extremely unfortunate, we need for this to continue if we wish for this cutting edge technology and wavelengths of medical breakthroughs to continue, unless there is some other method. Although these techniques may sound very simple, a large number of mice are killed in order to produce a breeding pair of transgenic mice, which raises many ethical concerns in debate of this subject. All the pups are given a hybridization DNA analysis to see whether they contain the transgene. Once the transfer of the genetically altered embryos is complete, the foster mother is allowed to go to term. The second technique commonly used to modify the genetic make-up of mice is called embryonic stem cell manipulation. Defective offspring can suffer from chromosomal abnormalities that can cause cancer fatal bleeding disorders, inability to reproduce, early uterine death, lack of ability to nurse, and such diseases such as arthritis, diabetes, liver disease, and kidney disease. Even though there may be many down-sides to genetically modifying animals, many people don't seem to realize that half of the things that exist in our world today must once have been tested on an animal.
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