The process of human fertilization. Where does the fertilization of the egg take place? Fusion of parent cells

The birth of a new life is a touching, amazing, almost fantastic process. Expectant mothers have always been interested in the question: how is the conception of a child. Two small autonomous cells, uniting, create a new person. And if the period when the fetus begins to move, for future mother more or less noticeable, the first days and even weeks of pregnancy remain “behind the scenes”.

Mother Nature is a wonderful and wise creator. Everything that concerns the continuation of the family, it is thought out to the smallest detail. Approximately in the middle of the menstrual cycle, a “marriageable girl” appears from the ovary - an egg ready for fertilization. It will remain ready for 12 to 36 hours. If during this time conception after PA (sexual intercourse) does not occur, the egg dies and is excreted from the body along with menstrual bleeding. Thus, conception by day after ovulation can occur in the period from one to three days. In some cases, during the period of ovulation, not one, but several eggs are formed. In this case, the likelihood of multiple pregnancy is high.

It is no secret how the fertilization of the egg occurs. Only one female cell is not enough for the birth of a new life. The immediate process of conception begins when potential "grooms" - spermatozoa - rapidly burst into the female body. Like heroes from fairy tales and epics, they have a long and dangerous path to their cherished goal. At the same time, the road is not close - from the cervix to the fallopian tube - about 20 cm. Given the tiny size of the sperm, this is a very decent distance.

First test

First of all, the "tadpoles" are in the vagina. This happens in the first seconds after the act intimacy. Here their first danger lies in wait. because of acid environment vagina weak spermatozoa (and most of them) die within 2 hours, never reaching the cervix. So, out of 500 million spermatozoa that enter the vagina after sex, only a third reaches the cervix. This is how natural selection works.

Second test

For successful conception there must be at least 10 million spermatozoa in the uterus. Not everyone will be able to achieve the goal, because the second barrier - the cervix, is no less difficult and dangerous. Wednesday also reigns here hyperacidity in addition, there is a mucous plug in the neck that interferes with further movement. True, during ovulation, the amount of mucus decreases somewhat. Mucus usually moves towards the spermatozoa, as if “washing away” the weak and indecisive on its way. The rest of the specimens have sufficient strength to move "against the current".

Third test

After passing the cervix, the spermatozoa end up in the uterus. reproductive organ helps the "tadpoles" in every possible way, increasing the speed of their movement. Gradually, they are begging for the last point - the fallopian tube. The catch of this test is that the tube is covered with epithelial cilia. Vibrating, they block the path to most applicants ultimate goal. So, out of the multi-million army of spermatozoa that ended up in the uterus, only a few thousand fighters remain in a row by the end of the fallopian tube.

During their movement through the uterus and tubes, spermatozoa change qualitatively, becoming capable of fertilization. Gentlemen are more patient: if the egg is “late”, they will expect it, and fertilization can take up to 3-5 days.

What happens after conception

Consider the fertilization of the egg by day. We will consider the first day of the life of an intrauterine baby not the day of sexual intercourse, but that great moment when the sperm meets the egg.

Day one: fertilization

And now the coveted egg is in the field of view of the applicants. They surround her in an attempt to complete the task.

But a reliable barrier stands in their way - the protective membrane of the egg. To break through it, the spermatozoa will have to try very hard. But nature again came to the aid of the "tadpoles" by putting an acrosome in their heads. This is a special substance that helps the sperm to dissolve the shell of the egg and penetrate inside.

Trying to break through the barrier, most of the "fighters" die, having exhausted their vitality. But the protective layer is weakened in some places under the action of the acrosome. At this moment, that very single sperm detects a "crack" in the membrane armor of the egg. He overcomes it and finds himself directly inside the egg.

Thus, the number of spermatozoa that have entered the vagina plays a primary role in conception. The statement that only one sperm is needed for fertilization is not entirely true. Millions of “tadpoles”, having gone through a difficult thorny path, thus make their way to one, the most successful one.

It is not always possible to predict with accuracy how long pregnancy occurs after ejaculation. This largely depends on the presence of ovulation, sperm motility and condition gynecological health women. The answer to the question when conception occurs after the act is ambiguous. On average, it can take up to 3 days from the time sperm enters the female body to a direct meeting with the egg. However, sometimes the partner's sperm are so tenacious that they are ready to wait for the egg for a whole week.

Day two-four: division

The sperm and the egg become one, forming a zygote. It will take about 36 hours after fertilization and the zygote will begin to divide. Still in the fallopian tube, the zygote is now a whole cell complex. modern medicine can accurately indicate on which day the division of the zygote will end. After the fourth day after fertilization, the division process is considered complete. The zygote is represented by two cells - blastomeres. In size, it remains the same, although the number of blastomeres will gradually increase. Future man needs space for growth and development. The pipe becomes cramped and uncomfortable.

On the third day, the zygote already has about 8 blastomeres, but still remains motionless. Only a day later, on the fourth day, the zygote of 16 blastomeres begins to move towards the uterus. At the same time, the blastocyst (embryo) itself remains tiny for all four days, practically not changing in size. This is necessary for easy access to fallopian tube. Full growth from this moment will begin directly in the uterus.

Days 5-7: Embryo in the uterus

For the first few days, a woman does not suspect that such amazing events are taking place in her body. Meanwhile, the embryo is already freely moving around the expanses of the uterus, in search of its place of residence. Having chosen a place convenient for himself, the future baby is attached to the wall of the uterus. The long and exciting journey is over. In this place he will live and develop for the next 9 months.

Days seven to twelve: implantation

The egg has implanted in the endometrium.

The zygote is in the uterus for 5-7 days after fertilization. After a few days (9-10 days following the fusion), the embryo will completely sink into the wall of the uterus. This process is called implantation. It lasts about 40 hours. It is reliably known how many days the implantation is completed - on the 12th day. From that moment on, the woman is considered pregnant.

After implantation, by about the 20th day of the cycle, a woman may experience certain symptoms, indicating that a new life was born in her body. These include:

• Implantation bleeding. It is often confused with menstruation. However, it is less abundant and ends, as a rule, on the same day it started. But if the smearers brown discharge last up to 10-14 days, a woman should immediately consult a doctor.
• The production of hCG - a special "pregnancy hormone". It begins to be produced 5-6 days after conception. It is because of him that a woman feels morning sickness, weakness or drowsiness.
• Sensitivity and swelling of the mammary glands;
• Increased;
• Rejection of certain odors;
• There may be a tingling sensation in the uterus or a feeling of heaviness in the lower abdomen.

All the described events occur in the body before a woman begins to miss her period or the main symptoms of pregnancy appear.

If the pregnancy is the first, a woman often writes off similar symptoms for common ailments. Ladies who have been in a position before are usually more sensitive to such manifestations and quickly guess about their pregnancy.

Days thirteen-twenty: delay

The most important sign by which a woman finds out about her pregnancy is a delay in menstruation. If it did not start on a certain day of the cycle, pregnancy can be suspected. Sometimes a delay can be caused by menstrual irregularities. One way or another, a woman should take a test to make sure her guesses are correct.

This period corresponds to approximately the 5th week of pregnancy. At this time, the fetus is still quite small - its size does not exceed 7 mm, and its weight is 4 g. But the doctor on the ultrasound will already be able to see it. The future person himself at this time resembles the letter C in shape. Despite its tiny size, upon careful examination, you can see processes on the monitor - future arms and legs. Sometimes you can even distinguish small tubercles in the region of the top of the processes - future fingers.

Facial contours also begin to appear during this period: dimples of the eyes and cheeks, nasal and oral slits. The tiny embryo floats freely in the amniotic fluid, which begins to be produced around the 5th week.

It is during this period that the rudiments begin to form. internal organs future person. On the initial stage formations are respiratory, circulatory and nervous system. Cells small organism continue to share. Very soon, the heart of the future baby will begin its work.

How to keep your baby safe

It often happens that a woman finds out about her pregnancy even before the results of the test and consultation with the doctor. Women's intuition tells the expectant mother that a new life is ripening inside her. But this is not always the case, and many women are unaware of their situation.

The first days and weeks are considered the maximum dangerous period for the future baby. After all, a potential pregnancy can end at any initial stage. That is why a woman should take care of her health and help her body in every possible way to accept a tiny creature.

To do this, you should follow some recommendations:

• It is worth preparing for conception in advance. For several months (ideally - for half a year), potential parents should stop smoking, drinking alcohol and other bad habits.
• The expectant mother needs to be carefully examined to study her women's health. The presence of inflammation or adhesive process in the uterus or in the tubes can lead to sad consequences. A fertilized egg, without passing through the adhesive barrier, can begin to develop in the fallopian tube and further lead to its rupture (ectopic pregnancy).
• A woman is recommended to drink. Especially recommended for expectant mothers are preparations containing folic acid and vitamin E. They significantly increase fertility (the ability to conceive).
• Proper nutrition should be a companion of a woman for the entire period of pregnancy. harmful products should be excluded from the diet, but water, on the contrary, should not be neglected.
• A potential mother is categorically not recommended serious physical exercise. Lifting weights should also be avoided. You can practice leading a calm lifestyle even before conception - the movements of the expectant mother should be smooth, unhurried and soft.

Pregnancy is a complex and simple process at the same time. It is complicated due to the fact that the baby goes a long way from the fusion of two cells to the birth. And at the same time, nature has simplified and thought through everything - the process of conceiving a child and its further development has been thought out practically by the day. From the expectant mother, only a little effort is required and unconditional love to the being within you to make childbearing as easy and enjoyable as possible.

fantastic video

Incredibly exciting and realistic video about the conception and subsequent development of the child. All about the intrauterine life of the future person. A touching and at the same time very informative fantastic video.

The process of conception depends entirely on the health of both partners. To establish it, you need to visit a doctor. Only after the permission of a specialist can you start planning a child. To reduce the timing of pregnancy planning, it is necessary to understand how conception occurs and on what days it is possible.

Couples wonder how a child is conceived. The process of conception is accompanied by the fusion of parent germ cells. In a man, the spermatozoon is involved in this. Sperm are produced in the paired gonads. The testicles carry out the daily production of germ cells. To liquefy the seminal fluid, a base is needed. It is formed in prostate. Influenced by work smooth muscle seminal fluid is excreted into the urethra and enters the female reproductive system.

It was found that the sex of the child is responsible for the chromosome carried by the sperm. For the birth of a boy, sex cells carrying XY chromosomes are needed. These substances affect the life of the sperm. Boy sperm are highly motile. They are able to enter the uterus during the first days after intercourse. Also due to this they have a short lifespan. The average activity is 48 hours. After that, they die.

Sperm with XX chromosomes are suitable for the birth of a girl. These sex cells move very slowly. They need time to get into the uterus. This feature is compensated by long viability. Such germ cells can remain active for more than five days. When asked whether it is possible to conceive a child of a certain gender, experts advise paying attention to this phenomenon. This data allows you to know how to conceive a child of a certain gender.

The work of the female body

Before you conceive a child, you need to establish the presence of a woman's fertility. An egg is needed to form an embryo. It matures in the ovary every month. The maturation of the cell depends entirely on the work hormonal system.

The menstrual cycle has three parts. They are called phases. The first stage is responsible for several important processes:

• maturation of the sex cell;
• preparation of the uterus for conception.

Preparation of the uterus consists in the formation of the endometrial layer. This tissue during the entire cycle has various properties. After menstruation, the tissue is a uniform thin layer that does not have a large thickness. Under the influence of estrogen, the endometrium gradually increases. The fabric begins to separate into several layers. For the onset of conception, the endometrium must have a thickness of at least 11 mm. This will allow the egg to firmly attach to the wall of the uterus.

The formation of an egg occurs under the influence of follicle-stimulating hormone. The substance appears in the bloodstream at the end of the first week of the menstrual cycle. Under its influence, the cell leaves the ovarian cavity and passes into its shell. Liquid accumulates under the shell. The egg and fluid form a follicle. Hormone causes active growth follicle.

From the second week of the cycle, luteinizing hormone replaces the follicle-stimulating substance. It gradually increases in number. On the 4th-5th day occurs sharp increase his level. Luteinizing hormone causes an increase in the volume of follicular fluid. She renders strong pressure on the walls of the follicle. They are torn apart. This phenomenon explains what the ovulatory phase is. When determining ovulation, a couple can know on which day fertilization occurs.

Time of pregnancy

Planning couples are interested in how long conception occurs after the act. Fertilization of the cell occurs in the fallopian tubes. The egg enters it after the rupture of the follicle during the first day. it auspicious time to conceive a child. During this day, the cell passes through the abdominal cavity. It is recommended to start at this time. Under the influence of smooth muscles, the cell moves towards the tubes and enters their cavity. When a cell fuses with a sperm cell, a zygote is formed. The zygote has an uneven structure. It should contribute to the faster advancement of the zygote along the fleecy layer of the fallopian tube. The villi move the zygote towards the uterine cavity. The move takes place within 2-3 days.

After the zygote enters the uterine cavity, it is introduced into the endometrial tissue. It gradually deepens into the layers of the endometrium and enters the wall of the uterus. The tissue allows the cell to attach more tightly to the uterine wall. The whole process takes 1-2 days.

From the moment of ovulation, the cell passes big way. Total time moving and securing is 5-6 days. From this point on, pregnancy begins. Given time may be shorter or longer. The timing of conception different women are individual. After how many days conception occurs, only a specialist can answer during the examination.

Signs of pregnancy

Patients ask how to find out if conception has occurred. In order for a woman to know how to understand whether conception has occurred, she must pay attention to a number of signs. The following first signs of conception are distinguished:

• the appearance of blood in the cervical mucus;
• pain in the lower abdomen;
• change psychological state.

Not many patients can pay attention to the listed signs. Some women experience conception symptoms such as blood in the cervical secretions. On the day when conception occurs, the zygote is introduced into the uterine wall. The walls of the uterine cavity are permeated with a large number of blood vessels. When the zygote penetrates the wall, part of the vascular fibers is damaged. After conception, blood enters the uterine cavity from the vessels. With a large volume of blood fluid, the mucus turns pink. A woman notices such signs of conception as a change in the color of cervical secretion. But this process is not mandatory for all women.

Has conception symptoms due to implantation. During implantation, pain in the lower abdomen may occur. Pain may occur due to damage to the uterine wall. This symptom appears when the zygote is attached to the anterior wall. Also, the symptom may occur on the day of ovulation. The process of conceiving a child can be recognized by the presence of pain during the appearance of an egg from the follicle shell. From this point on, a woman can determine how long it will take to develop a pregnancy. The location of the pain also matters.

A woman should be able to guess about the conception of a child by changing her psychological state. This process causes various changes in the body. A few days after conception, the hormonal system is restructured. Progesterone is responsible for the development of the embryo. This hormone appears in the blood from the moment the zygote is fixed. Its main volume is in the corpus luteum. It should form at the site of the burst follicle. Under the influence of progesterone, there is a change psycho-emotional state. Conception in women is accompanied by tearfulness, irritability and drowsiness. After the disappearance corpus luteum this symptomatology disappears. These symptoms allow you to determine whether implantation has occurred or not.

Conditions for speeding up the process

Couples ask how fast conception occurs. To this end, it is necessary to follow the rules of conception. They are needed by both future parents.

A man needs to follow the following points:

• rare sexual contacts;
• giving up alcohol and smoking;
• active physical activity;
• undergoing a medical examination.

Seminal fluid is able to quickly change its qualities. Its characteristics are negatively affected various factors. In order for the conception of a child to be successful, it is necessary to observe sexual rest. Before the start of the fertile period, it is not recommended to have sex for a week. Since the onset ovulatory phase sexual contact should be done every other day. After pa, the concentration of seminal fluid decreases. The break promotes the accumulation of mature and motile spermatozoa in the fluid. The accumulation of healthy germ cells increases the concentration of seminal fluid, which promotes conception.

Since spermatozoa are sensitive to any negative impacts, before starting planning, you should stop drinking alcohol. Alcoholic drinks have a detrimental effect on sperm. If a man has been abusing alcohol for a long time, a break in planning for 3-4 months is recommended. This will help the body cleanse itself of decay products and recover.

For everything to work out, you need to conduct active physical activity. Conception can only happen when normal operation reproductive system. Vigorous physical activity increases metabolic processes in the small pelvis. The acceleration of blood circulation causes an influx of oxygen to the tissues. This allows the cells to multiply more actively. Sperm is updated faster, which affects the conception of a child.

Also, before starting planning, you need to undergo an examination by a specialist. The physician must full examination. Medical control will determine the condition of the male reproductive system and its ability to fertilize. This will make planning go faster.

The woman is also given advice for conceiving. Tips for conceiving a child include the following recommendations:

• ovulation tracking;
• taking a certain posture after conception;
• the use of vitamin complexes;
• proper nutrition and physical activity.

Pregnancy can only occur during the ovulatory period. To establish it, it may be necessary various ways. The main method is to plot temperature indicators. It is measured daily in the colon. The obtained data are entered into a table. The plotting takes place throughout menstrual period. After conception, it is also recommended to take a measurement in order to make sure that conception has occurred and that you have managed to get pregnant.

After conception, it is recommended to maintain physical peace. A woman should lie down for 20 minutes after intercourse. She must understand that any movement can cause the seminal fluid to be expelled from the vagina. For conception to occur, experts advise taking the birch pose. This pregnancy-promoting tip is used by many planning couples. The adoption of this posture allows the seminal fluid to quickly penetrate into the uterine cavity. In this case, conception can be obtained faster. Other methods of conception are also used.

Various vitamin-mineral complexes can also influence the ongoing process. Vitamins should be taken on the days of the menstrual cycle. The procedure for taking and the type of medication should be carried out by a doctor. You should not do this on your own. A woman does not know what happens under the influence of certain vitamins. The process of conceiving a child can be disrupted.

There are other factors that affect the onset of fertilization. A woman should know what to eat right. When planning, fried, fatty and salty food. You should also refrain from using spices. The patient needs to be active image life. This enhances metabolic processes.

These conditions are taken into account when planning a second pregnancy. The conception of a second child should also be carried out through the timely preparation of parents.
Modern doctors often face a complaint that children do not turn out for a long time. To determine the cause of the disease, you need to visit the hospital and study the process of conception.

Fertilization of the egg - a process from A to Z in time

Called the heroic story of one sperm. Yes, this is indeed a whole story for the microscopic world.

Conception is the greatest mystery, in which there is still unsolved - all the mechanisms have not been fully studied.

1. Processes prior to fertilization
   • Ovulation
   • Transport of the egg into the tube

• Fusion of gametes
• Formation of the genome

Processes prior to fertilization

The meeting of gametes (female and male) is preceded by many events:

• The maturation of the oocyte (future mature egg) and sperm - sperm.

• - the process in which the female germ cell leaves the ovarian follicle (the place where maturation took place).

• ejaculation - ejaculation male cells with seminal fluid into the genital tract of a woman and overcoming a path that entails great losses.

• Capation (activation) of spermatozoa.

The movement of male sex cells

During intercourse, approximately 300 million sperm enter the vagina. All but one, the most active and resilient tailed "lucky one", will die on the way to the egg. The losses are colossal, but nature dictated this:

• Almost immediately after intercourse, millions of spermatozoa flow out along with the semen.

• Millions die in acidic environment vagina.

• Losses will be during the passage cervical canal cervix under the action of cervical mucus.

• Some spermatozoa will get stuck in the folds of the cervical mucosa (they will become a reserve group that will strive for the oocyte if the first group does not meet with the egg).

Fertilization of the egg is possible only after ovulation. If sexual intercourse is performed before the release of the egg, then the stuck sperm can wait for ovulation already in the woman's body. Their life span varies from 24 to 168 hours (up to 7 days). That is, you can get pregnant if intercourse was before and after ovulation. Using this information, you can future baby.

Contact with a slightly alkaline environment of mucus cervical canal leads to an increase in the motor activity of spermatozoa. After which they move faster.

Inside the uterus, muscle contractions help sperm to move. However, mistaking spermatozoa for foreign bodies destroy thousands of sperm. The surviving sperm cells move into the fallopian tubes. One half goes into the empty fallopian tube, the other goes into the fallopian tube containing the unfertilized egg.

Moving along the tube, the spermatozoa move against the flow of fluid and some get entangled among the villi of the mucous membrane. AT upper divisions of the genital tract, under the action of biochemical substances, reactions are triggered, due to which the capatization of spermatozoa occurs. The membrane covering the sperm head changes. Spermatozoa acquire the ability to fertilize and become hyperactive.

Ovulation

Two weeks before menstruation, regardless of the length of the cycle,. If the cycle is 27-28 days, then the exit from the follicle occurs approximately in the middle of the cycle. The duration of menstrual cycles in women varies and can reach 45 days or more. Therefore, when calculating the day of ovulation, it is more correct to focus on the expected start of a new period and count 14 days from this date.

Ovulation happens like a small explosion. The follicle filled with fluid in which the oocyte "ripened" bursts. And the egg, together with the follicular contents, is in abdominal cavity. But at the same time, she "does not get lost."

Transport of the egg into the tube

The ovary is covered with fringes of the fallopian tube, which, thanks to the ciliated epithelium on inner surface guide the egg - point it in the right direction - towards the entrance. Cilia of the epithelium are activated under the action of hormones - estrogen, secreted by the ovary after ovulation. Their movements are coordinated and unidirectional. At this stage, the egg is surrounded by cumulus cells that form the radiant crown. During the fertilization of the egg, the sperm will have to overcome this layer in order to reach the outer layer of the female germ cell.

Fusion of gametes

Fertilization of the egg is carried out in the ampulla of the fallopian tube, located closer to the ovary. Only a few dozen sperm cells reach this place. They overcome the radiant crown and reach the shiny shell - the outer layer of the egg. Then they attach to specialized receptors on its surface and begin to secrete proteolytic enzymes that allow them to “dissolve” the protein shell and pass through the protective layer. Under the protective shell is the inner membrane of the egg, and only a thin layer of fluid separates the sperm from it.

Having overcome the last obstacle, the sperm, which first reached the inner shell, attaches to it. Within minutes, the membranes of the sperm and egg fuse. The egg "takes" the sperm inside. This event entails a chain of biochemical reactions, causing change in the shell. Spermatozoa can no longer attach to it. The fertilized egg then releases substances that repel other spermatozoa and becomes impermeable to them.

Formation of the genome during fertilization

Inside the egg, the densely packed genetic material of the father unfolds. A shell is formed around it - the pronucleus or the precursor of the nucleus. Inside the pronucleus, the genetic material rearranges itself into 23 chromosomes. Maternal genetic material under the influence of the process of fertilization of the egg completes its formation.

Microtubules are web-like filaments that bring both nuclear precursors closer to each other after their flat formation. Two sets of chromosomes combine to form a unique genetic code, which determines hundreds of characteristics of the body (skin color, nose shape, etc.). - completed. Ahead is the path through the fallopian tube to the uterus, and the further development of the embryo for 9 months, childbirth.

Consists of several concepts that characterize the possibility of conception. Therefore, the time characteristics are given in the table.

Table 1.

The timing of fertilization of the egg

Fertilization of an egg is not always the same as pregnancy. Because in order for the pregnancy to begin,.

Successful development of the embryo depends on the formed genome. An embryo with an incorrect set of chromosomes most often dies before or after implantation and exits along with menstrual flow. And the woman doesn't know what short span time "was pregnant." For her, it was just a delay.

A rather complicated process of merging two cells. It is amazing what nature has been able to create in the process of evolution, because we almost never think about all the intricacies of the process of conceiving a child. The human body is so complex and self-organized that in 9 months a new life has time to form in it - another person. In this article we will talk about how fertilization and conception of a child occurs.

conception process

You need to prepare mentally and physically for the conception procedure. First you need to take the path of truth: lead an active lifestyle, stop drinking and smoking, start eating right, etc. These truths, although they look simple, have a profoundly positive effect on the processes of conception and the unborn child. It should be noted that ignoring these rules is simply unacceptable, especially for those couples who have repeatedly, but unsuccessfully, tried to give birth new life.

Did you know? During sexual intercourse, 150 to 250 million spermatozoa are ejected.

Many people wonder how to conceive a child the first time, but most of them do not know about such a thing as fertility. In fact, it is very important characteristic procreation process. is the ability female body to the conception of a child. When the follicle matures in the ovary, an egg comes out of it, which is already ready for the mechanisms of fusion with male spermatozoa. This factor is the basis of a normal and rapid conception process, which takes an average of 2 weeks. During this period of time, the following stages occur in the body of a woman:

1. Fertilization of the egg.
2. Cleavage of embryonic cells.
3. Implementation of the embryo and its attachment to the mucous membrane.

How does this happen

The mechanism of fertilization of the female egg and the further development of the embryo is a whole science. Below we will briefly describe the scheme of fertilization and talk about where in the body of a woman such a complex process occurs.

During sexual intercourse, the sperm in the male testicles begin to show activity. After some time (2-7 minutes), they begin to move along the vas deferens. When spermatozoa reach the seminal vesicles, the process of their fusion with the seminal fluid takes place. After that, they become ready for the fertilization of the female egg.

Together with seminal fluid, sperm make a long journey through urethra men and then under high pressure fall into the feminine. Millions of mobile male reproductive cells from this time begin to strive forward, in search of an egg.

Important!British scientists have found that smoking women are 22% less likely to successfully conceive.

The main task of mobile "cavaliers" is now the introduction into the uterine cavity, and then into the fallopian tube. On the way to achieving their goal, millions of sperm will be killed. immune system female body. They are selected according to the laws of genetics: only those cells remain that are the strongest and capable of producing healthy offspring.
Then everything happens as beautiful pictures, or in an instructional video titled "how to make a baby". About a hundred of the surviving and strongest sperm surround the egg. Only one can penetrate into its cavity - the chosen one and the most suitable (according to genetic parameters). When that same unique sperm enters the cavity of the egg, the process can be considered started.

Splitting up

On the this stage male and female sex cells merge into one. Now their genetic material fuses and becomes one. A day later, the process of division of the formed cell begins, which lasts about 96 hours. After this time, the embryo already consists of 32 cells.
In general, the crushing mechanism proceeds in geometric progression, that is, with each act of division, the number of cells doubles. It should also be noted that division occurs both at the stage of advancement of the embryo to the uterus, and at the stage of implantation, and, accordingly, at the stage of formation of all organs and systems.

Entry of the embryo into the uterus

After the successful fertilization of the egg and the start of the crushing mechanism, the process of attaching the embryo to the uterus begins. The advancement of the embryo through the fallopian tubes begins already with fourth day and continues until the seventh day. For about three days, the embryo is in "free swimming" and is looking for a place to attach to the uterus. At this point, there is always a possibility.

Did you know?The male sex cells (sperm) are 85,000 times smaller than the female egg.

After four days after the start of conception, the zygote turns into a blastocyst. During the "journey" through the fallopian tubes, the embryo accumulates necessary substances, which will further contribute to the normal processes of implantation. Also at this stage, villi begin to break through on the blastocyst, which serve as a food element. During this period, the mother's body is also preparing for the attachment of the embryo: hormones that make the uterus begin to be actively ejected favorable place to join.

Implantation of the embryo into the uterus occurs on the fifth day after the start. In total, the implantation process proceeds as follows:

1. After the embryo clings to the uterine mucosa, the latter will begin to fill with fluid. As a result of this filling fertilized egg gradually adheres to the endometrium.
2. The next step is adhesion. Adhesion - the beginning of the interaction of the embryo and the uterus through the villi.
3. The last step is invasion. At this stage, the embryo destroys the lining of the uterus and joins the blood vessels mother. From this point on, the fetus has a common blood flow with the mother. At the time of invasion, a pregnant woman may experience minor uterine bleeding, which do not entail dangerous consequences.

Auspicious and unfavorable days

An important milestone on the way correct conception child is keeping a diary. Every woman should follow the regularity, as there are days on which it is simply impossible to start the process of a normal pregnancy.

If a menstrual cycle standard and regular, it is possible to calculate the days for the most favorable conception of a certain child. With chaotic critical days there is always a breach hormonal background, which interferes with the normal mechanism of the birth of a new life.

Important!To successfully conceive a new life, a woman needs to drink 8 glasses pure water in a day.

Whole critical cycle can be divided into favorable and bad days to conceive a child.

by the most favorable periods considered to be:

• Period 2-4 days before ovulation.
• The true moment of ovulation.
• The next 24 hours from the start of ovulation.

• Any of the days of the menstrual cycle.
• 48 hours after the end of ovulation (an egg that has not come into contact with a sperm simply dies).
• The first 48-72 hours after the end of critical days.
• 6-7 days before ovulation.

Did you know? Spermatozoa cover such a long distance to the egg that if they were the size of a person, their path would be 6,500 kilometers.

Fundamentals of successful conception of a child

Over time, each couple has thoughts about replenishing the family with a child. It is not always possible to give birth to a new life, because some factors sometimes interfere with the normal process of conception. There are many rules that must be followed couples who wish to bring themselves and the world one more person:

One of the most amazing processes that take place in human body, is fertilization, or the process of conception. How wonderful it is - after all, only two small cells give rise to a future person! Now the fertilization process has been studied in detail, and every woman planning a pregnancy or just dreaming about it should understand everything. physiological basis fertilization.

During sexual intercourse in the process of ejaculation, about 250 million sperm enter the woman's vagina. What is it for? After all, this great amount! This is provided because not every spermatozoon will pass all the barriers and obstacles on the way to the egg, and as a result, the fastest and healthiest will participate in the process of fertilization. Immediately after entering the vagina, spermatozoa find themselves in a destructive environment: the acidity of the vaginal environment is about 4, that is, very high. That is why after two hours most of the sperm will die. But the surviving mobile cells will continue on their way.

The next obstacle is in the cervical region. Most days of the menstrual cycle the cervix is ​​full thick mucus, which is a natural obstacle to microorganisms. But during the period of ovulation, cervical mucus becomes less thick, and spermatozoa can penetrate through it into the uterine cavity. For a number of conditions cervical mucus even during the period of ovulation, it is too thick, and this prevents the passage of sperm; in such cases in question about cervical infertility. It is believed that for the successful completion of the fertilization process, at least 10 million sperm must enter the uterine cavity.

The spermatozoa that have entered the uterine cavity continue to move towards the egg, moving towards the ovaries through the fallopian tubes. In the fallopian tubes, the flow of fluid is directed away from the ovaries to the uterus, therefore, the spermatozoa meet another obstacle - they are forced to move against the current.

By this time, the egg itself had also gone through a long and difficult path of preparation. All eggs in women are laid in the ovaries by the time of birth, and their number no longer increases. Each menstrual cycle, one egg goes through certain phases of maturation and growth. When the egg is ready for fertilization, the follicle ruptures and it ends up in the abdominal cavity near the fallopian tube. Normally, under the influence of directed movements of the villi and fluid flow, the egg immediately enters the fallopian tube, where fertilization will take place. In some cases (for example, in the presence of adhesions or post-inflammatory changes), the egg does not enter the fallopian tube, and then its fertilization can occur directly in the abdominal cavity; as a result of this, an ectopic pregnancy is formed.

fertilization process

The fertilization process itself normally occurs in the fallopian tube, or rather, its ampullary section (the part of the fallopian tube that is closer to the uterus). But here, too, the sperm meets obstacles. The egg is covered on the outside with dense shells that it needs to overcome - a radiant crown and a shiny shell. The process of destruction of the membranes of the egg in the zone of penetration by the sperm is called penetration. To destroy the area of ​​​​the membranes on the head of the spermatozoon, there is hyaluronidase - a substance with which the extracellular matrix is ​​split between the cells of the radiant crown. For sufficient destruction of the intercellular matrix, several spermatozoa are required, one cannot cope with this. It is the sperm that will first penetrate the zona pellucida and carry out the process of fertilization.

After penetrating under the layer of the first membrane, the sperm cell destroys the cells of the zona pellucida with the help of acrosomal enzymes. The acrosome is a modified lysosome, a vesicle containing the necessary enzymes. It is located on the head of the sperm in its anterior section. When the spermatozoon reaches the zona pellucida, the receptors on its head interact with the ligands located on the second membrane. There is a process of "recognition", after which the acrosome is connected to the shell, and its contents are directly on the shell, destroying it locally. Local thinning of the zona pellucida allows sperm to active movements get inside and be close to the cytoplasmic membrane of the egg.

On the surface of germ cells (egg and sperm) there are specific receptors that allow the fusion process to take place. After the sperm head penetrates the egg, its mitochondria and centriole are directly at the target. From this moment, within an extremely short time, a cortical reaction of the egg occurs: in the vesicles located on its surface there are special enzymatic substances that, when merged with outer sheath the eggs modify it so that other sperm can no longer get inside. Thanks to this, a block of polyspermy occurs - preventing the penetration of the genetic material of more than one spermatozoon. This reaction develops within a few minutes. Extremely rarely, however, the penetration of two spermatozoa occurs, which leads to the formation of a triploid embryo (having a set of chromosomes from three cells, and not from two, as is normal). At further development In such an embryo, chromosome anomalies occur, such embryos are not viable and die within a few days. It should be correctly understood that if two sperm enter the egg, this does not give rise to the development of identical twins, but leads to the formation of a non-viable zygote.

After fertilization

As a result of the fusion of the egg and sperm, a zygote is formed - this is a single-celled phase of embryo development. At this level of development, it is within 24-30 hours, during this period, the formation of pronuclei - the nuclei of germ cells. The genetic material of each sex cell - male and female - has a haploid set of chromosomes. The formed pronuclei approach each other, then their shells dissolve, and their genetic material is combined.

An already fertilized egg continues its movement along the fallopian tube, which is facilitated by the movement of the villi and the contraction of the walls of the tube. During this period, the zygote is crushed - its division with the formation of a multicellular embryo; the total size of the zygote does not yet increase. The cleavage period lasts about three days, and the cells of the zygote at this time are called blastomeres. Initially, all blastomeres are the same - both in size and in determination. They still do not interact with each other and remain together solely due to the shiny shell. If for any reason this shell is damaged, the embryo will simply crumble into separate cells.

From the fourth day of embryo development, the process of blastomere differentiation begins - two layers of cells are formed. On the fifth day of development, a blastocyst is already formed - a developmental stage with about 30 cells, which looks like a hollow ball with a group of cells attached inside to one of the walls. If two such groups of cells are formed inside the embryo at this period, this will give rise to identical twins.

After entering the uterine cavity, the embryo must attach to its wall. During this period, its cells are already closely interacting, and for better contact with the uterine mucosa, hatching occurs - the embryo is released from the shell. The cells of its upper layer throw out processes that are tightly immersed in the glands of the endometrium and provide trophism. Under the influence of progesterone, the endometrium increases, tightly surrounding the embryo from all sides. secreted by embryonic cells chorionic gonadotropin(that hormone increased content which is detected by pregnancy tests) affects the ovaries, stimulating their production of progesterone to prevent the onset of menstruation.

In embryology, the period of development of the embryo is always counted from the moment of fertilization. In contrast, in obstetrics, it is customary to consider the gestational age from the first day of the last menstruation before pregnancy. This is due to the fact that each woman ovulates at an individual time (approximately in the middle of the cycle), and it is impossible to know exactly this day without a special diagnosis.

Thus, the most amazing and complex process takes place - fertilization. Coordinated work of all body systems, overcoming difficult barriers to hit the best sperm, the finest interaction of physiological and biochemical levels- all this leads to the beginning of a new life, to the beginning of pregnancy.