chromosome painting - into the amniotic sac and fluid is...

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chromosome painting Complex probes made from entire chromosomes can be made. In this way the presence that chromosome can be ascertained and also whether it has been subject to any rearrangements. This picture shows a probe made from chromosome 22 which has been used to "paint" a cell line which has a small mysterious extra chromosome. The probe hybridises to this as well as to the two normal chromosome 22s showing that the small "marker" chromosome is derived fromm chromosome 22. prenatal diagnosis If there is some reason to suspect that an embryo may have abnormal chromosomes, for instance maternal age or past history of early spontaneous abortions, it is usual to check. At about 12 - 14 weeks of gestation it is possible to obtain foetal cells by amniocentesis . In this technique a needle is inserted
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Unformatted text preview: into the amniotic sac and fluid is drawn off. Foetal cells, amniocytes, are suspended in the fluid and these can be cultured and their metaphase chromosomes examined. One of the commonest chromosome abnormalities is Down syndrome, the figure links to the relevant passage later in this lecture. • At 9-10 weeks of gestation, it is possible to aspirate via the cervix, a small amount of the placental tissue, the technique of chorionic villus sampling . This tissue can be cultured and chromosomes prepared. • In fertility clinics embryos are often conceived by artificial insemination. A single, totipotent, cell from an 8 cell stage embryo can be examined directly and the information can be used to decide on which embryo to reintroduce into the mother....
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