A group of Cambridge scientists has made a discovery that will help to better understand the processes of embryonic development and develop methods to combat genetic abnormalities of the fetus. Studies have shown that any fetus has everything necessary to form a full-fledged child, and scientists have been able to establish (for the first time in the history of science) at what stage of formation it can be understood that in the future the organism will have any deviations.
One of the employees of Cambridge, Professor Magdalena Zernitska-Getz, who became the author of the revolutionary study, at one time experienced a difficult experience associated with her pregnancy. At age 44, Magdalena, who then nursed a second child, the doctors reported that the results of the placenta biopsy indicate that her child, possibly, will be born with Down's syndrome. As doctors explained, in the placenta, about 1/4 of the cells were with abnormalities, and offered the woman to have an abortion. After questioning her colleagues, Magdalena found out that with these test results, to say with an accuracy of 100% that the baby is born with deviations is impossible and this affected the decision of the woman to leave the baby, who was born in the put period completely healthy. This prompted the woman to think more deeply about the development of embryos in order to reduce the number of abortions associated with inaccurate analyzes.
The researchers studied rodent embryos, some of whose cells contained the wrong amount of chromosomes, after a series of experiments it was proved that in the early stages of development, some anomalies in the chromosome set might disappear. Experts created embryos with the wrong sets of chromosomes, but observations showed that abnormal cells die due to apoptosis (the mechanism of cell death), while healthy cells continued normal division process.
In the first experiment, the abnormal and healthy cells mixed 50/50, in the second 3/1, but the result was similar, with the only exception - part of the abnormal cells did not die, but at the first and second experiment the biopsy showed the presence of abnormal cells that confirms the possibility of an error, what happened in the case of Magdalena.
The human embryo contains 23 pairs of chromosomes, one of which is sexual (XY and XX), and the remaining autosomes. Changes in the number of chromosomes lead to various abnormalities of fetal development, the most common example is Down's syndrome, when the 21st chromosome has three copies, instead of two.
As a rule, such violations become the main cause of death of newborns, the only viable form of the disorder is trisomy (the formation of three copies of autosomes), which occurs with the development of Down syndrome.
Most often, the formation of three copies occurs in the 16th chromosome, which invariably leads to miscarriage.
The absence of one of the chromosomes (monosomy) has more severe consequences, since in this case the fetus dies, except for the loss of one of the sex chromosomes in women causing Turner's syndrome -deviations in mental and physical development (dwarfism).
Additional copies in sex chromosomes do not adversely affect the development of the embryo, but the children may have mental retardation.
In women after 40, there is a higher risk of developing disorders in the chromosomal set. Now there are tests that suggest the presence of genetic pathologies. From the 11th to the 14th week, women are offered a chorion biopsy, in which samples of the placenta are extracted and studied for the number of chromosomes.
There is also another test in which cells of amniotic fluid are studied (appointed from week 15 to week 20) and the results of this study are considered more accurate.
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