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Ovum - what you need to know?
Ovum - what you need to know?
Anonim

The egg is the largest cell in your body. Nevertheless, almost nothing is said about her at school. Check it out: what if some information was unknown to you before.

Ovum - what you need to know?

Two Scientific Facts You May Have Forgotten About Eggs

Types of oocytes

Let's start with the basics. The ovum is a special cell. The scientific world has a whole system of its classification. According to the position of the yolk, the human ovum belongs to the acelital type, because it is not in our cells. In addition, in the process of evolution, humans as a species have developed a completely special path of embryonic development, so that the nucleus in human eggs is located in the center and therefore they are also considered isocytic. Among other things, the egg is called so precisely because it looks like an egg and contains parts that are visually similar to it.

Ovum what you need to know

Are you familiar with the largest cell in your body - the egg?

Development and structure of the egg

Egg development begins with the growth of follicles located in the ovaries. A mature female ovum is spherical and contains the following parts:

  • The nucleus from which the egg cell begins to divide after fertilization
  • The primary membrane that separates the egg from other cells
  • Yolk inclusions
  • A lustrous shell covered with a radiant crown (it plays a protective role and nourishes the cell)
  • The polar body (this is where the inactivated X chromosomes in the egg are located, which are transferred by the mother to the embryo during the formation of DNA for dose compensation of genes).

How many eggs are in the female body

The maturation of the egg is strikingly different from the development of the sperm. In men, reproductive cells are constantly produced and, say, a young man behaved badly in April, and then changed his mind and corrected himself, then July sperm cells may turn out to be of quite high quality. A woman's egg cell is much more sensitive because it is not renewed and the entire "set" of germ cells is released from birth. All the harmfulness that you at least in 5, even in 30 years loaded into your body, will settle in the body. Remember: every bad habit greatly impairs the quality of the egg and can affect the health of the unborn baby, so you need to take care of yourself.

The number of eggs in a woman is limited, but there are a lot of them. At birth, both ovaries of a newborn girl contain about two million follicles, where the egg lives, as well as her future "sisters" in the form of oocytes. All of them are dormant until puberty, but some die before you flourish.

What you need to know about the egg

The ovum is a unique part of the female body. Do you know well how it develops and what is it responsible for?

By the time of the first menstruation (menarche), only three hundred to four hundred thousand full-fledged eggs remain in the body of a future woman. On average, a woman's reproductive age is 40-46 years, so from the beginning of menstruation to their termination, you have to go through about 300-400 menstrual cycles. Approximately the same number of eggs (on average 1 egg per cycle) will eventually mature in your body and some of them will have a chance to create a new life. At the same time, 2 eggs rarely ripen, but if this happens, a woman has a chance to give birth to fraternal twins when pregnancy occurs.

How does egg maturation take place?

The mechanics of the process is such that the development of the egg begins in the ovary in a special follicle. At the same time, the egg does not live alone: ​​in the first phase of the menstrual cycle, a small number of follicles begin to grow actively. They release female sex hormones into the bloodstream - estrogens. The more follicles are included in this race, the more hormones enter the bloodstream and the more your femininity is manifested.But after ten days, all the follicles, except one, regress. Once this happens, all of them can be written off, except for one - the dominant follicle. He alone continues to grow until a full-fledged egg cell is formed.

The dominant follicle grows larger (up to 2 cm in diameter) until it bursts and releases the egg towards the sperm into the fallopian tube, where fertilization can occur. Actually, this moment is called "ovulation" (from the Latin ovum - "egg"). It usually occurs in the middle of the cycle, about 14-16 days before menstruation. The release of the egg is accompanied by changes visible on ultrasound: the edges of the ruptured follicle in the ovary collect, like a bud, and form a corpus luteum. It is it that, in the second phase of the menstrual cycle, begins to produce another female sex hormone - progesterone, which is necessary for the maintenance and development of pregnancy.

I see the goal! What does the egg do in the uterus

Nobody will allow an egg cell to swim for a long time and to swim far. The egg cell does not live long after ovulation, so almost immediately it is picked up by the fimbria of the fallopian tube and driven into the funnel: further it can only move towards the uterus. The sperm and the egg must meet in the fallopian tube, but this is already the initiative of the sperm: it strives for unity, while the egg itself, not paying attention to the "boyfriend", continues to make its way to the final destination of the journey. Fertilized or not, the egg will get there! The egg, after entering the uterus, will already decide what to do next: if the sperm has entered it, it will begin to settle down, fixing itself in the endometrium - the inner, mucous layer of the uterus: for the next 9 months it (that is, not quite she) will spend here. If the ovum finishes its journey alone, it will send a signal to the corpus luteum and die. The corpus luteum will also cease to function and endometrial rejection (menstruation) will begin. In this case, it is not difficult to calculate how long the egg cell lives. She has 2 days for this whole trip.

Ovum ovulation

Ovulation is a process that captures all systems of the female body and affects not only the ability to conceive

How does egg ovulation occur?

  1. Here the scheme is clear: ovulation occurs on average 14 days before menstruation and lasts 48 hours. And just in these 48 hours conception is most likely - the egg is no longer in the ovary, it moves towards the uterus. But we know that "in general" and "on average" is not always the case for everyone and not always. Sometimes the circuit gets blocked and stops working. Therefore, you should not study the general rules, but your own body.
  2. The ovulation rhythm can change with endocrine diseases, after abortion, childbirth. There are menses without ovulation and ovulation without menses. Breastfeeding mothers and women in menopause are often confident that they are not in danger of pregnancy. Sometimes this leads to different incidents like “Darling, we are going to have a baby. Again…"
  3. Young mothers should be aware that the process of egg maturation is inhibited only if the break between breastfeeding does not exceed three hours during the day and four at night. I decided to rest longer - and that's it, you're at risk. Even women over 50 cannot sleep well. The reproductive function fades away gradually - sometimes the maturation of the "late" egg is possible. European gynecologists are sounding the alarm: a frivolous attitude towards contraception is increasingly leading to the pregnancy of women after menopause.
  4. 2-3 cycles per year without ovulation is a medical norm. Count it up. If the duration of your cycle is 21-23 days, and your period is 6-7 days, then ovulation occurs immediately after your period. Strong love excitement and stress also lead to unexpected results. Additional ovulation may occur. Especially without a permanent partner. And with an irregular menstrual cycle, ovulation and menstruation may coincide in time.All this means that the mathematical calculation of "safe" or "favorable" days is useless and even harmful.

Features of ovulation of the egg

It so happens that the leader in the race is not revealed, and at some point all the follicles stop growing. None of them get big enough to burst and help arrange the meeting of the egg and sperm. Doctors call this "polycystic ovary syndrome" and consider it the most common cause of infertility. Fortunately, this is now being treated.

There is also another side of the coin. A sperm cell retains its reproductive properties for almost twice as long as an egg cell! Hidden in the nooks and crannies of your reproductive system, he can treacherously wait for her for three or even four days. Therefore, pregnancy sometimes occurs, even if sex was on a "safe" day. In this situation, there is also a risk that the fertilized egg will not reach the uterus and attach in the tube, causing an ectopic pregnancy. Therefore, for any unusual course of menstruation (delay, scanty discharge), buy a test as soon as possible and contact your gynecologist! First of all, it is necessary to exclude an ectopic pregnancy.

Fertilization of the egg

The oldest way to calculate ovulation is the calendar. But it is not very reliable. Therefore, humanity has always sought to invent something more convincing.

The first scientific method was to measure basal temperature. Every morning, without getting out of bed (after 6 hours of sleep), you measure the temperature in the rectum. Then you build a graph and see where the flat line grows sharply. This will be the day of ovulation. But the basal temperature, in addition to the function of the ovaries, is affected by inflammatory diseases, an increase in body temperature, intercourse 3-4 hours before its measurement, alcohol. So the method is as unreliable as it is anti-erotic.

The first ovulation test strips appeared over 20 years ago. They look and work like pregnancy tests. One strip - no ovulation, two - there. Sometimes a color change is an indicator.

Some tests determine the onset of ovulation by saliva. The "answer" is visible through a microscope. The structure of saliva during ovulation is different from that on other days. However, there is a great risk of wishful thinking.

The most reliable ways to "catch" a day favorable for conception is to determine the hormonal background and an ultrasound scan 3-4 days before the expected ovulation of the egg, in general, doctors will help you with this. And we have collected tips that answer the question of how to get pregnant faster.

Egg donation and other times when assisted reproductive technologies are needed

ART - assisted reproductive technologies - is a set of measures applied to people who dream of having children, but who do not have the natural ability to do so. ART includes IVF, germ cell cryopreservation, egg donation, surrogacy and other methods suitable for both men and women.

Some ladies have to seek the help of reproductive specialists due to physiological characteristics. For example, when your oocyte supply has dried up and you need a donor egg. Or when a woman focuses on her career and postpones pregnancy for over 40 years. In this case, she can pre-freeze the egg, and then return to the issue of childbirth. Also, ART is indispensable if there is a problem of obstruction of the fallopian tubes or they are absent. IVF usually helps in this situation.

How IVF works

IVF - extrapolar fertilization, perhaps the most famous of all reproductive technologies. It is prescribed when a woman does not have fallopian tubes or is obstructed, and when other methods have failed.

IVF allows you to achieve the desired pregnancy in almost hopeless cases, but this process is not quick. It consists of the following steps:

Ovarian stimulation and follicular growth monitoring

The essence of this stage is for the ovaries to produce as many follicles with eggs as possible in one cycle. It is believed that the younger the patient, the more they will turn out and the better the eggs are formed in the ovaries.

Follicle puncture under ultrasound control

On the 8-10th day of stimulation, each female ovum is ready for puncture and high-quality material is obtained from mature follicles. When stimulated, two eggs, or 3 eggs, can mature. Or maybe 5 eggs, 9 or much more. No matter how many of them there are, everything will be taken away during the puncture and, together with the follicular fluid, will be placed in a special test tube.

In Vitro Fertilization

At this stage, active sperm are added to the test tube to the eggs, where each egg survives for another five days after fertilization.

The first day of embryo growth

Hooray! A miracle happened, fertilization took place, but this is only the beginning of the journey. It is on the first day after fertilization that each bad zygote, a fertilized egg, is discarded if genetic selection does not pass. Each healthy egg contains 23 pairs of chromosomes, the same number of them in the sperm. If everything goes right, they connect to create a healthy embryo. If not, the embryo dies.

The next stage is from the second to the fifth day of embryo growth

Doctors continue to observe and evaluate the quality of the egg cell division. The division must be uniform and correct.

Ovum IVF

A healthy egg is a key success factor for IVF

Embryo transfer

Approximately on the sixth day after fertilization, the grown embryo is transferred into the uterine cavity of the expectant mother. It usually doesn't hurt at all.

Confirmation of pregnancy

Ten days later, the woman donates blood for hCG to confirm the fact of pregnancy, and two weeks later she does an ultrasound to make sure once again that everything is fine with the embryo.

Since not all cells survive even with IVF, at the stage of stimulation they are "grown" with a reserve so that about 4 eggs are obtained at a time. Good extra embryos are frozen and sent to a cryobank, where all the genetic material that the egg donor gave is stored. If a woman is able, it is better for her to donate the egg herself, but if this is not possible, she can consider donor programs and choose the future genetic mother of her child.

Of course, it will be great if everything is in order with your health and you can calmly dispose of your eggs as it suits you. But if you suddenly have difficulties in order to become a mother, do not be afraid to try different methods. Now in the arsenal of doctors there are technologies that can solve almost any problem.

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