2023-04-30 20:00:00
According to experts, up to 1 in 3 eggs that are fertilized do not become implanted in the uterus or they will end up as a miscarriage that happens even before implantation. And it is that, the whole process that happens from the moment the egg leaves the ovary until it remains attached and implanted in the uterus is much more complex than is usually thought.
In a social moment like the one that is being lived at a global and national level, in which science and politics are increasingly determined to determine when does life really beginKnowing and understanding what the process that starts pregnancy is like is a key piece in the dilemma.
AN INVISIBLE AND COMPLEX PROCESS
In many cases, sexual education reduces and simplifies the beginning of pregnancy to say that the egg produced by the ovary is fertilized in the interim tube and adheres to the uterus, where the embryo begins to develop. However, before this fertilization, there is a series of processes that the ovum has to develop to reach that point in the right conditions to face fertilization.
In the same way, after the union between spermatozoon and ovum, the journey through the interim tube continues involving different phases that are crucial for the zygote to develop and that allow, at the end of this process, a person to give birth. positive on a pregnancy test.
The time that elapses between the exit of the ovum from the ovary and the moment in which a confirmation of pregnancy by a test is possible is, at least, 6 days. In all that time there is ovulation, fertilization, division, the journey through the uterine tubes, the complexity of entering the uterus and, finally, implantation in the endometrium of the uterus.
DAY 0: OVULATION
For an individual with female genitalia, from the arrival of puberty begins a process known as ovulation. It is from this moment when, in cases of a regular cycle, once a month a small ovum that is developing in the ovary reaches its point of maximum maturation and leaves the capsule that keeps it isolated to enter the uterine tube.
Los ova are not created: an individual who is born with ovaries will already be born with all the ovules that they will have throughout their life, that is, between 1 million and 2 million. Each month of the menstrual cycle, about 1,000 ovules they are activated, but only 1 of them, or two in some cases, reaches the perfect point of maturation to leave the ovary.
Portal Drauzio Varella
Representative illustration of the uterine fimbriae
To go outside, the ovule is transported by the calls uterine fimbriae: fringe-shaped endings that are found in the most distant part of the fallopian tube and that “embrace” the ovary. The ovum passes into them and moves along their ends until it reaches a well-formed area of the tube. In turn, the ovum is protected by two layers: an inner one known as the zona pellucida (gelatinous layer of protein) and an outer one called corona radiata (responsible for the nutrition of the ovule).
From the moment the ovum leaves the ovary, it has 24 hour “shelf life”in which fertilization can occur.
DAY 1: FERTILIZATION
Once the sperm enters the uterus, it goes up to the fallopian tubes and travels through the uterine tube looking for the egg. If it finds it, the male gametes face the difficult mission of coming into contact with it. It will be necessary that the first to arrive break through the protective layers of the ovule, that is, the zona pellucida and the corona radiata, sacrificing itself and opening the way for the later ones.
By the time one of them reaches the heart of the egg, no one else will, as this will be in charge of issuing its genetic material inside. This moment is known as fertilizationalthough it is erroneously popularly labeled as conception, and it occurs less than a day after the egg leaves the ovary.
No, you were not the fastest sperm
Each egg and each sperm has 23 chromosomes with genetic material. By coming together and combining, they give rise to a completely new cell, created as a union of both genetic materials, which will contain the 46 chromosomes arranged as pairs of 23. It will be this combination of genetic information from the egg and sperm that, together, will give rise to a completely new one that will define the hundreds of characteristics of the new individual.
DAYS 2, 3, and 4: DIVISION AND TRIP
About 30 hours after fertilization and in a very slow process, the unicellular zygote begins to divide as it moves along the uterine tube. These new cells are known as blastomeres. The divisions in this stage of the journey continue until the creation of 12 or more blastomeres, at which point they undergo compaction and are called the morula, whose shape is reminiscent of a blackberry with small joined circumferences. In fact, its name comes from the Latin mulberrywith meaning “mulberry shape”.
Pascal Goetheluck / Science Photo Library
Microscopic view of a morula
Throughout the journey through the tubes and uterine tube, these cavities act as drive tubes. The walls are full of cilia, that is to say, small structures that simulate being tails that vibrate and which help the movement of the ovule throughout its entire journey.
DAY 5: ENTRY INTO THE WOMBEN
Four days after fertilization, the blastomeres of the morula rearrange, giving rise to a new type of cell assembly known as blastocyst. This presents different parts, such as an enveloping layer, an internal cavity and a cell accumulation at one of its poles. Of all these, some will become the placenta, and others the embryo itself. It is at this time that the blastocyst reaches the uterus and finally leaves the tubal tube.
Also, while all that travel and transportation process was going on, the uterus was undergoing a series of changes to prepare for the arrival and facilitate the implantation of the ovum. Among these modifications, the one that stands out the most is the thickening of the endometrium. This is a hollow, muscular lining of the pelvis that covers the inner wall of the uterus.
Part of the immune system is sacrificed during pregnancy
Thus, about a week after fertilization, the blastocyst is at the entrance of the uterus. If the process of thickening of the endometrium has finished and has occurred successfully, in the following days the blastocyst will be able to adhere to it, implant itself, and begin embryonic development. The lifespan of the blastocyst, that is, the days that it can remain in the uterus before “dying” they are fourTherefore, if it has not been implanted at that time, for one reason or another, it will be expelled from the body without the person knowing anything about the process that has occurred.
DAY 6: THE IMPLEMENTATION
Up to this point, the effects for the person do not exist, that is, they have not experienced any symptoms: the process is invisible even for doctors. But with implantation, everything changes.
At this time, the body begins to prepare for embryonic development and the beginning of the pregnancy situation. The endocrine system now begins to generate enormous amounts of the hormona hCG, which is present in urine and is detectable in a pregnancy test. It is also at this time that those with a regular menstrual cycle will have noticed a certain late periodfirst symptom that, finally, the pregnancy is beginning.
#process #occurs #pregnancy #decisive #occur