After fertilization, the egg expects a long and difficult path to implantation in the uterine endometrium. According to statistics, more than half of them will not pass it. In this case, the woman does not even know that a new life began to arise in her.
On average, embryo implantation occurs a week after fertilization. All this time, the egg moves through the fallopian tubes and actively develops, preparing for this event. 20 hours after fertilization, it is divided into two parts. After this, the egg is already called a zygote. During its journey, it repeatedly divides to form a solid ball of many cells. When their number reaches 16-32, then the zygote becomes morula. If it is divided into two parts, then we get twins. When the morula reaches the uterus, it already consists of an average of 64 cells. Some of them will develop into a fetus, while the rest will form membranes and the placenta.
Morula gradually turns into a ball filled with liquid. After that, she is blastocyst. The surface layer of cells will become a placenta, and those that are inside will develop into an embryo. It is at the blastocyst stage that the fertilized egg enters the uterus.
This is normal, however, if the fallopian tubes are impassable for some reason, implantation of the embryo can occur directly into their wall. An ectopic pregnancy is occurring, which poses a danger not only to the reproductive health of a woman, but also to her life.
How successful the implantation of the embryo into the uterus will go depends on whether the latter is ready for this. Once in it, the blastocyst still develops in free swimming for several days. The hormone progesterone plays the main role in preparing the uterus for implantation.
The thickness and sensitivity of the endometrium is very important here, since the embryos that start interacting with it are not implanted if it is not ready for this. The most successful time for the introduction of a blastocyst into the uterus is the period from 20 to 24 days of the menstrual cycle. The endometrium at this time is most susceptible to it, since a large number of active substances are produced.
The blastocyst during implantation penetrates into it by cells, and tissue breaks with the release of blood. Sometimes the endometrium is not nutritious enough for her, then a miscarriage happens.
If the implantation of the embryo was not successful, then it is excreted through the vagina. According to statistics, about 40% of blastocysts that enter the uterus do not invade its mucous membrane.
If implantation was successful, then the development of the placenta and the production of the hCG pregnancy hormone by the embryo begin. He needs about 2 weeks to firmly gain a foothold in the uterus. During this period, a miscarriage is possible, but not as likely as immediately after implantation.
Some organs and systems of the embryo are already beginning to form. In these two weeks, it is still possible to divide it into two parts and the formation of two fruits. If it happens later, Siamese twins are obtained.
Many future mothers are interested in whether it is possible to find out that implantation has occurred. It turns out there are several signs that this has happened. So, embryo implantation: symptoms:
- on the graph of basal temperature there is a sharp decrease (implantation subsidence) on this day.
This is due to the fact that after the blastocyst is introduced into the endometrium, a sharp release of estrogen occurs, which leads to a decrease in temperature. By the way, it is because of him that it is low in the first phase of the cycle.
Thus, implantation of the embryo is accompanied by a decrease in basal temperature and, in some, a slight bleeding. According to statistics, it occurs successfully only in 60% of blastocysts, and the rest are excreted. A very dangerous pathology is its attachment to the wall of the fallopian tube in case of obstruction. The journey and development of a fertilized egg lasts about a week. For successful implantation, the sensitivity and thickness of the endometrium is very important .