Immediately after fertilization, an intensive process begins - the crushing of the egg. Two cells turn into four, then they become eight, after a few weeks they become an embryo. It has already laid the main organs, and in 9 months it will become a newborn baby.
How long does the egg fertilize?
The process of fertilization of the egg lasts only a few hours. The spermatozoon breaks through the layer of the epithelium, which surrounds the egg, penetrates into its shell and reaches the nucleus. In the process of fertilization, the sperm uses special enzymes that are located on the front end of the head, which help to overcome the protective barrier. After this, the ovum is no longer available for other spermatozoa, cell division begins.
Oocyte division
As a result of the fusion of the ovum and the sperm from the fertilized egg, a zygote develops, the first stage of the development of the embryo. Within the next 24 hours, it will be a unicellular organism that will gradually begin to degenerate into a more complex structure. In the zygote, the process of formation of nuclei (male and female) is actively underway. Each of these nuclei has its own set of chromosomes - male and female. The nuclei are formed at different ends of the zygote, they are attracted to each other, the shells dissolve and crushing begins.
The daughter cells formed as a result of division become smaller, they exist in the same shell, and do not interact with each other. This period lasts up to three days. After another day, the cells form a blastocyst, which consists of 30 cells. This is the initial stage of development of the fetal egg, a hollow ball with an embryoblast attached to one of the walls - a future baby. Blastocyst is fully ready for implantation in the epithelium of the uterus.
Symptoms of oocyte fertilization
Fertilization occurs at the cellular level, and therefore is invisible to the woman. That is why it is difficult to distinguish symptoms typical for the fertilization of an egg. The first signs of pregnancy can be felt only after the fertilized egg is attached to the uterine cavity, and this will happen, on average, 7 days after the fusion of the sperm and the egg. This moment may manifest as a slight bleeding, which a woman can take for the onset of menstruation. In addition, immediately after attaching the egg in the body, the hormonal background begins to change, and then the first signs of pregnancy begin to appear. Usually this occurs no earlier than 1.5-2 weeks after fertilization.
Why is not the egg fertilized?
In some cases, even though the ovum and sperm meet, there is a violation of conception. For example, it may happen that an unfertilized oocyte is found immediately with two spermatozoa, resulting in the formation of
In any case, to answer exactly the question of why pregnancy does not occur in any particular couple, only the doctor can after a thorough examination, since many different factors affecting both the sperm and the egg should make up for the fertilization to come together.