Fertilization describes the joining of the egg and the male sperm. Both nuclei fuse and combine a portion of the mother’s DNA with that of the father. After fertilization, the egg begins to divide and develop into a baby ready for birth within 9 months.
What is fertilization?
Fertilization describes the union of the egg and the male sperm. Eggs and sperm differ significantly from every other body part by one feature: they contain only half a set of DNA. The purpose of this is to allow the mother or father to contribute half of his or her DNA, thus creating a human being who gets half from both parents along the way. Of course, this also happened when the father and the mother of the child were created – thus there are almost infinite combinations in which the half DNA set can be present. For example, one reproductive cell may contain the predisposition to blond hair, the other to red hair. Fertilization is only possible if the woman and man have sexual intercourse on the woman’s fertile days. These are the days just before ovulation and during the migration of an egg through the fallopian tube to the uterus. Sperm move around independently, with recent observations suggesting that only a few sperm are ever intended to fertilize the egg. All others work in concert to ensure that these sperm are transported forward to the egg. A single sperm penetrates the egg cell through its outer envelope and advances to the nucleus. The nucleus of the sperm, which has meanwhile triggered its flagellum, fuses with it – fertilization is complete. The egg cell now only changes its cell membrane so that no further sperm can penetrate.
Function and task
Fertilization is the basis of human reproduction. If it does not happen or does not happen properly, the woman cannot become pregnant and cannot have a child. About every 28 days, a new egg is ready for fertilization and waits on its way from ovary to uterus for male sperm to fertilize it. Fertilization must be error-free because it involves passing on and recombining the DNA of the parents, which means it has a high potential for error. Risks begin with the creation of eggs and sperm and end with external influences such as radiation during fertilization, which can affect them and the cell division that happens afterwards. Important for the woman during fertilization is the presence of a healthy mucous membrane in the uterus, otherwise the egg cannot implant. Thus, there would be no pregnancy. In men, fertilization depends heavily on the quality of the sperm for it to work smoothly.
Diseases and ailments
Normally, the woman notices little of the fertilization. The first sign is often only the absence of monthly bleeding. If, on the other hand, the egg has nested, that is, fertilization has been successful, some women, however, quickly develop the first symptoms of early pregnancy. The age of the parents, their way of life and external influences such as radioactive radiation or illnesses of the parents can have a strong influence on fertilization. It is a particularly crucial point in pregnancy and also in the life of the coming child, as DNA plays a major role here. If an egg or a sperm divides incorrectly or if an error occurs during the fusion of the two cell nuclei, a more or less serious congenital disease can result. Unfortunately, neither the woman nor the man have much influence on this – there are only examinations of the embryo to determine its health. Particularly well-known diseases that arise from errors in the DNA during fertilization are Down syndrome or metabolic diseases such as phenylketonuria, which almost always make everyday life difficult for the child. If a serious mistake happens during fertilization, sometimes the woman’s body already recognizes it. The fertilized egg can still implant and the woman realizes that she is pregnant, but soon after an abortion occurs. It resembles menstrual bleeding and is therefore sometimes not recognized as an abortion. Since there is no health threat to the woman, this does not require medical attention if everything goes without complications.Especially in the case of older parents, problems with fertilization can be due to the fact that sperm and egg cells change qualitatively. However, modern medicine now knows methods of artificial insemination, which have proven to be very efficient when a woman or man has developed problems with fertilization. Often, instead of treating the underlying problem, artificial insemination is performed directly. The procedure is often used for hormonal problems at fertilization, sometimes accompanied by hormone therapy for the woman to allow for healthy pregnancy after fertilization. Very few problems with fertilization today actually result in unwanted childlessness; most are easily treated.
