Instead of a preface. So, we all know from childhood that women get pregnant from sperm entering their body. Moreover, the carriers of male genetic information are spermatozoa that mature in the testicles. This is known to the world biological science 300 years. It must be said that in terms of the volume of sperm in the ejaculate, there is not so much. When in laboratory conditions the sperm is centrifuged and the sperm precipitate, their volume making up 5 percent of the total sperm volume. The rest is the secret of the seminal vesicles, prostate gland, bulbourethral glands. It contains a lot of high and low molecular weight substances that provide sperm with normal living conditions, sources of energy, protection from the acidic environment of the vagina and from the immunological attack of the female body, substances for ripening and suitability for fertilization.
Part one. The life of a sperm male body.
The sperm matures in 72–74 days. The first stages are numerous divisions (first by mitosis, then 2 meiotic divisions) in the testicular tubules. Thus, the male reproductive cell, called a spermatid at this stage of development, receives its characteristic half set of chromosomes. And, in principle, it is suitable for fertilization if someone (an embryologist, for example) forces it to penetrate the egg. For conception to occur in a natural way, the male reproductive cell must have 3 properties. Firstly, the ability to reach the egg, and secondly, to penetrate the membranes of the egg and, at the same time, keep the priceless paternal genetic material intact. Spermatids acquire all these properties when passing through the epididymis. Their tail grows, a motor apparatus is formed, the head becomes smaller, the head cap matures - an acrosome with a set of enzymes for corroding the membranes of the egg, DNA is assembled more tightly for preservation in a foreign environment. female body. Mature sperm are obtained. However, in the epididymis they live quietly, like mice: they hardly move, breathe little, and protect themselves until they reach a woman. If sperm stay too long in a man's body, they will age and become unsuitable for fertilization.
Practical conclusions:
Sperm matures for a long time - 2.5 months, so when planning pregnancy it is necessary to exclude harmful effects(antibiotics, cytostatics, anti-inflammatory drugs, occupational hazards) in advance.
According to most scientists, the optimal quantitative and qualitative composition of sperm for conception is obtained during sexual activity once every two days. Therefore, if the spouses have irregular sex life (due to business trips of 2 weeks or more, for example), the likelihood of conception decreases. However, in our experience and according to the literature, the variability of ejaculate parameters is very high. U different men the number of sperm varies tens of times; in the same man, the concentration, mobility, and morphology of sperm can vary by 2-3 times, depending on the period of sexual abstinence, the intensity of physical or emotional stress.
Here I would like to digress from the main narrative to the problem of “deterioration” in sperm quality over the past 50 years. Such facts are often cited both in specialized and popular literature. I think it's not that bad. How do we know the composition of sperm 50 years ago? From the archives of sperm banks. However, there are 2 “buts” here. First: what was the period of sexual abstinence when donating sperm? Often 4-5 days, this is the time frame recommended by reference books on andrology or laboratory diagnostics previous years. And now WHO recommends abstinence laboratory research sperm 2-3 days. What is the difference between ejaculates after abstinence of 2 or 5 days, the author of these lines observes under a microscope every day (with a longer period of sexual abstinence, the number of sperm increases, but their motility and morphology worsen). Second “but”. Who goes to donate sperm to a sperm bank? Men are sexually liberated, with a strong sexual constitution (not everyone likes to masturbate into a jar) and, moreover, selected medical commission. That is, those who did not have enough sperm by the standards of those years, even if they had children, simply did not end up in the sperm bank, and, accordingly, in research studies male fertility(fertility, that is) of past years.
But actually, why are there tens and hundreds of millions of sperm in the ejaculate, if one is enough for fertilization? We are often asked the question. See part 2.
Part two. Life of sperm in the female body.
Spermatozoa come to life, begin active movement and, accordingly, metabolism from contact with sperm plasma, which occurs at the moment of ejaculation. To meet the egg, the sperm has to travel through the cervical canal, the uterine cavity and most fallopian tube. This advancement is largely facilitated by the contraction of the smooth muscles of the female genital tract. Moving deeper into the female body and having less and less contact with the sperm plasma, sperm begin to prepare for possible fertilization.
Changes occur on the surface of their heads, the tails begin to beat overactively, which further promotes recognition of the egg and penetration into it - the so-called capacitation (from the English cap - cap). Capacitation is only the first stage of sperm readiness. The second stage of readiness for fertilization will include further ultrastructural and biochemical changes on the surface of the sperm head (fusion of the plasma membrane with the outer acrosomal membrane, formation of hybrid membrane vesicles, loss of the acrosomal cap). These changes are called the acrosomal reaction. After its passage, sperm are fully suitable for fertilization, exhibit chemotaxis to the egg (recognized by smell) and are able to destroy its membranes. The lack of ability to undergo the acrosomal reaction of sperm, even with all other normal parameters of the spermogram, is a factor in infertility. A classic example is infertility caused by taking antihypertensive drugs of the nifedipine group. Acting according to the mechanism of blockers calcium channels, these drugs interfere with the passage of the acrosome reaction by sperm, making their users temporarily infertile.
However, if capacitated spermatozoa can be compared to a semi-finished product that is suitable for consumption for quite a long time, then after undergoing the acrosomal reaction, spermatozoa are active for only 2–3 hours. And if during this time they do not meet an egg (which, by the way, lives for 2 days after leaving the ovary), then they disappear forever. Fortunately for the safety of the human race, the second stage of sperm maturation does not occur with all cells at once, but spontaneously, first with some, then with others (just as atoms of radioactive elements do not all decay at once). A mature egg is an inducer of the acrosomal reaction.
The egg is surrounded by many spermatozoa and together they lyse its membranes with their acrosomal enzymes: hyaluronidase, acrosin, etc. (By the way, the drug lidase, used for lysis of scars, is made from bull semen...). As soon as one sperm penetrates the egg, a block of polyspermy is formed - we do not need children with a triple or more set of chromosomes. The most rapid barrier to the penetration of additional sperm is provided electrical changes in the membrane of the egg, a little later - chemical and structural.
The nuclei of the sperm and egg, now called the male and female pronucleus, respectively, come together, merge and begin to fragment. The impetus for the fragmentation of the zygote is given by certain proteins contained on the surface of the sperm.
The splitting zygote descends into the uterine cavity in 7-8 days and attaches to it (implantation, conception, conception). From this moment on, pregnancy tests begin to work effectively.
Practical conclusions:
So, you need a lot of sperm because: not all of them reach the fallopian tube, not all of them mature immediately, a large number of sperm is involved in the lysis of egg membranes.
Sperm can live in the female body and retain fertilizing ability for several days. Therefore, the day of conception and the day of fertilization may not coincide.
In some cases, during laboratory testing of sperm, all indicators may be close to normal, but the man is still infertile, due to invisible subtle biochemical disorders.
Sperm move independently in seminal fluid. However, it is not known how they behave once they enter the female genital tract: whether they constantly move or sometimes stop moving; whether the substances necessary to restore the energy spent on movement are obtained from the products of the environment in which they live, or together with the seminal fluid. But since we know that sperm stored in an incubator at body temperature and protected from drying out remain alive for more than 8 days and are in constant motion during this period, we can assume that they maintain their mobility throughout the entire time they are present in the female genital tract .
The lifespan of sperm in the body is determined by researchers in different ways. Some authors believe that it is 24-36 hours, others - 8-14 days.
Under a microscope, the speed of movement of a sperm is approximately 3 mm per minute, i.e., in a second it moves the length of its body. When moving, a lot of energy is consumed, since the sperm is forced to overcome obstacles and move against the flow. And since the flickering eyelashes of women fallopian tubes set the direction of this flow, the sperm always move towards the ovary. The capillary nature of this flow naturally reduces their speed. It is believed that in the uterus, sperm travel 1-1.5 cm in 3 minutes, i.e., to leave the seminal mass, enter the uterine pharynx and from there rise into the uterine cavity, the sperm needs approximately 1.5-3 hours. A few hours later, they can be found at the side of the fallopian tube, where they connect to the egg. Only one sperm penetrates the egg, its head fuses with the nucleus, and this fusion, in essence, is fertilization.
If these calculations are considered correct, then fertilization occurs no earlier than 8 hours after sexual intercourse. The question arises: after what period of time can fertilization not occur, unless, of course, there was repeated copulation? The answer is not easy. But the results of observations give reason to believe that this period can be very long. It is possible that a sperm can fertilize an egg even 8-10 days after copulation. Some researchers believe that if sexual intercourse took place before menstruation, sperm can survive in the tube and fertilize the egg afterward. menstrual period. This hypothesis cannot be rejected unconditionally, especially when it comes to early ovulation. It is currently accepted that sperm can remain motile in the cervical mucus or tube for 7-8 days, but their fertilizing ability remains approximately 24 hours.
What happens to sperm that do not reach the egg? After all, the egg can only accept one sperm and after that it is closed to everyone else. And since with each copulation 200-500 million sperm enter the vagina, it is clear that a countless number of them die. Some sperm leave the vagina along with the sperm that flows out of it. The remaining, also significant, part quickly dies in the vagina under the influence of high acidity vaginal discharge. Spermatozoa can live only in moderate acidity, which occurs in the vagina at certain times, as well as in the weak alkaline environment of sperm, uterine mucus, and tubal fluid.
Dead spermatozoa decompose. Their remains flow out of the vagina or are removed by rinsing. On the other hand, their breakdown products, as well as other substances contained in sperm, are absorbed by the vaginal wall and enter the body.
A small part of the sperm enters the uterus and moves towards the tubes, but most of them die along the way. Since the susceptibility of the uterine mucosa to sperm breakdown products is greater than that of the vaginal walls, some sperm penetrate directly into this lining. They were found there between the cells at all stages of decay, and it is clear that in this state they are absorbed even better and replenish the body's juices.
Ultimately, very few sperm make it to the fallopian tubes. And there they all, except one, who fertilizes the egg, die. However, no one noted their presence in the mucous membrane of the tubes. Probably, the remains of dead sperm are carried by capillary flow into the uterus.
Some sperm, which are able to resist longer and have the greatest mobility, sometimes reach the abdominal cavity.
As shown by experiments with the introduction of sperm into abdominal cavity, there the sperm are devoured by phagocytes (white blood cells), which provide protection to the body, are digested and disappear within approximately twenty hours.
How long do sperm live? Sperm viability - important medical indicator along with the concentration total number and motility of male germ cells. Data such as the lifespan of sperm are of primary interest to many couples of different ages who are planning a new addition to the family. In addition, a semen analysis aimed at determining this indicator will help identify infertility in men; it is indicated for unsuccessful attempts to conceive for more than six months, planning a pregnancy, or before artificial insemination.
- 1. The birth and life of sperm in a man’s body.
- 2. Existence in the external environment.
- type of external environment;
- temperature;
- light exposure;
- exposure to synthetic compounds;
- acid-base balance;
- chromosome set of a particular sperm;
- quality, quantity and activity of male reproductive cells.
- do not wear too tight trousers or uncomfortable underwear;
- give preference to loose, non-tight underwear in the form of shorts (boxers or so-called family underpants);
- avoid prolonged hypothermia of the male genital organs;
- avoid exposure high temperatures(several weeks before the planned conception, it is not recommended to visit baths and saunas).
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Mechanism of fertilization
A sperm is a male reproductive cell, which, when it enters the female body, favorable time and at suitable conditions fertilizes the egg, resulting in pregnancy. With a successful combination of circumstances, fertilization occurs on average within 1.5-2 hours after completion of sexual intercourse and only if the sperm enters the vagina, i.e. when sexual contact occurred without the use of barrier or hormonal contraception. Sometimes conception can occur even hours or days after intercourse.
One egg can be fertilized by only one sperm, but for successful conception it is necessary that at least 10 million male germ cells penetrate the uterus. The fact is that conception is a very difficult process. Sperm, firstly, after sex must enter the woman’s vagina, where most of them die due to increased acidity, secondly, male cells overcome the cervix and fallopian tubes, the last frontier is the protective membranes of the egg. The success of conception at this stage largely depends on such factors as the viability and number of sperm.
After fertilization, the egg moves through the fallopian (uterine) tubes and is fixed in the uterus, implantation occurs. At this stage, the “all or nothing” principle works, i.e. a kind of natural selection occurs. If a woman’s body is affected by certain negative factors at this time, then the embryo may not have enough reserves to cope with them. But in the event that the fertilized egg successfully attaches to the uterine cavity and overcomes the influence negative factors, the pregnancy will develop further. Doctors say that every second woman planning to conceive a child loses her pregnancy at this stage, without even knowing that successful fertilization has occurred.
Cell life cycle
Conditionally life cycle male reproductive cells can be divided into 2 stages:
Spermatogenesis, i.e. The formation of male reproductive cells begins during puberty. The full life cycle of a sperm lasts on average about 3 months. If ejaculation does not occur during this time, the sex cells die. In this case, sperm lose the ability to fertilize a female egg within 20-30 days after their final maturation in the male body.
In the male body, sex cells are born and finally mature within 2 months. Sperm production is regulated by the hormone progesterone, and the process of spermatogenesis occurs in special male gonads (testes). An important factor, affecting the formation of viable germ cells in sufficient quantities, is the temperature in the testicles. The most active and healthy spermatogenesis occurs at 32 °C, best option- several degrees below body temperature.
After conception and until the moment of ejaculation, sperm are located inside the male body - in the epididymis, and during ejaculation they are mixed with the liquid fraction of sperm. After this, the final stage of life of the germ cells begins: they either die after some time in the open air, or enter the woman’s vagina and have a chance to fertilize the egg under other suitable conditions.
How long do sperm live in the external environment? The vitality of male germ cells depends on a large number of factors and conditions. Very generally, experts call the time period when sperm is capable of fertilization and is active outside the male body, a period from 15 minutes to 1 week, or even 14 days.
What factors influence viability?
The fundamental condition affecting the viability of sperm in the external environment is the health of the male and female organisms and their readiness to conceive. In addition, not only physical readiness for pregnancy is important (i.e. the onset of ovulation in the near future, production sufficient quantity sperm, etc.), but also a positive psychological attitude. It has been scientifically proven that emotional condition has a significant impact not only on the success of the conception process, but also, for example, on effective treatment various diseases occurring in acute or chronic form, for prevention and elimination inflammatory processes different internal organs and systems.
The lifespan of germ cells is a purely individual factor for each individual man. This indicator, as well as the ability to conceive in general, will help to accurately determine the sperm analysis - spermogram.
Other factors that influence the lifespan of sperm include the following:
The lifespan of sperm carrying Y and X chromosomes differs. According to popular belief, it is indeed somewhat more difficult to become pregnant with a boy than with a girl. The fact is that germ cells carrying the Y chromosome (if fertilization is successful and pregnancy continues, a boy will be born) live only about 24 hours, while sperm containing the X chromosome (a girl will be born) are able to maintain sufficient activity for 3 days .
So making a boy is truly a jewelry job for a man, because it is necessary that sexual intercourse without the use of contraception occurs on the day of ovulation. Although on this moment There are no accurate plans for planning the sex of the unborn child if unprotected contact occurred a maximum of a day before the expected ovulation, the probability of the birth of a son is indeed quite high.
How are environmental conditions affected?
An important factor influencing the viability of male germ cells is temperature environment. Most favorable temperature regime for semen activity outside the male body, this is the normal human body temperature, i.e. 36-37 °C. Temperatures exceeding this indicator negatively affect the activity of male germ cells - sperm at high temperatures die in a much shorter period of time than at normal conditions.
At low temperatures, male reproductive cells are immobilized; despite this, they retain the ability to successfully fertilize an egg. It is this feature that is used for long-term storage of sperm in special storage facilities. Sperm banks allow semen to be frozen in liquid nitrogen for subsequent artificial insemination at least 6 months after the material is received in storage.
The death of sperm is promoted by bright light, especially natural light (i.e. direct sunlight). The acid-base balance of the environment has an influence: in an acidic environment, sperm activity decreases and life expectancy decreases; in an alkaline environment, on the contrary, germ cells are activated. An important condition is the impact of various synthetic compounds contained in artificial lubricants or condoms - in this case, sperm die much faster than under normal conditions.
Lifespan outside the body?
The lifespan of male germ cells in the external environment may vary. The main factor that influences this indicator is in this case is the type of environment surrounding the sperm. Sex cells are active for varying periods of time in the open air, in water, in a condom or in the body.
In air, male reproductive cells can only live for a short time. Factors that influence them outside human body(i.e. in an unfavorable environment), have far from positive influence. Almost immediately (within 15-20 minutes) sperm are killed by bright light, high or low temperature environment. But when room temperature and without exposure to direct sunlight, sperm can retain the ability to fertilize for even several hours. When male reproductive cells come into contact with underwear, a napkin or similar materials, the lifespan of sperm increases slightly.
When sperm dries out in the open air, the activity of the germ cells, and therefore their ability to fertilize an egg, is significantly reduced. At the same time, the chance of pregnancy still remains for some time after the ejaculate has dried. Fertilization is possible, for example, by mechanically transferring sperm from a napkin, hands or underwear to the female genital organs.
On the surface of the body, as a rule, sperm are also active for several hours and retain the ability to fertilize an egg for some time after drying (on average no more than half an hour). On the penis or female genital organs, the conditions for maintaining the activity of male reproductive cells are better than on any other surface (for example, a napkin, fabric, etc.). Suitable humidity and temperature allow the liquid fraction of sperm to not dry out longer, which means that sperm are able to fertilize the egg over a longer period.
What happens in a woman's body?
In a woman’s body, male reproductive cells are capable of retaining the ability to fertilize an egg for different periods of time, depending on the woman’s health, sperm quality, and phase menstrual cycle.
A week before ovulation or a few days after, sperm can survive in a woman’s genital tract for no more than 2 hours. The quality and viability of sperm in this case is negatively affected acidic environment vagina, which is necessary for the female body to disinfect the genital organs and maintain normal microflora.
If unprotected sexual intercourse resulting in ejaculation occurred at the appropriate period, i.e. shortly before or during ovulation, sperm remain active enough long time. Sometimes a seed that enters a woman’s genital tract can wait up to several days for the egg to mature.
As a rule, in the first half of the menstrual cycle, the vaginal microflora is less acidic than after ovulation has occurred, so that the sperm that managed to end up in the uterus and fallopian tubes in the first 2 weeks from the last critical days They may well fertilize the egg in the middle of the cycle (i.e. after its maturation).
Being in the water
How long can male reproductive cells survive when placed in water? In water, sperm suddenly lose their activity and ability to fertilize. When released into the aquatic environment, sperm remains in a state suitable for the possibility of pregnancy for no more than a few minutes.
At the same time, there is a difference in the survivability of sperm in the seminal fluid and in the form of a separate germ cell. As a rule, male reproductive cells, connecting with the liquid fraction of sperm, are active and viable for a longer time than if for some reason they were separated from the seminal fluid. Thus, sperm lives in an aquatic environment for up to 5-10 minutes, and an individual sperm will die almost immediately (within a few seconds).
Purely hypothetically, of course, the possibility of pregnancy from sperm entering the water exists. But experts rightfully argue that in practice under normal conditions this is completely impossible. In order for fertilization to occur from sperm entering the aquatic environment, for example, while taking a bath, at least several liters of seminal fluid must be in the water. So be afraid unplanned pregnancy when visiting a public swimming pool, it’s definitely not worth it.
How to improve sperm health?
The quality of sperm, its quantity and sperm activity directly affect the likelihood of conception.
You can find out whether these indicators are normal if you take a spermogram in medical clinic from a qualified specialist.
To improve sperm quality and sperm viability, doctors give the following recommendations to men:
It is undesirable to use artificial lubricant or various gels, since they significantly shorten the lifespan of sperm and inhibit their activity.
A woman is not recommended to douche; the procedure disrupts the acid-base balance of the vagina and washes away a special lubricant that helps sperm move faster to the uterus. In addition, the fact that a woman has an orgasm increases her chances of getting pregnant, because... The natural contraction of the vaginal muscles promotes the movement of male reproductive cells towards the uterine cavity and fallopian tubes.
Scientists call the ability to reproduce offspring by the Latin word “fertility” (fertilis means “fertile, fruitful”). To carry out this process, certain conditions are required. If at least one link in this chain drops out, pregnancy either does not occur or occurs congenital pathology fetus Necessary conditions for pregnancy are:
1) maturation of the follicle in the ovary, its rupture, release of the egg (ovulation) and formation of the corpus luteum 1 in place of the follicle;
2) the ability of sperm to penetrate the uterus, fallopian tubes and fertilize the egg;
3) free passage of the egg and embryo through the fallopian tube into the uterine cavity;
4) the readiness of the uterus to implant (implant) an embryo.
A favorable combination of the above circumstances, with the spouses in full health, with regular sexual activity in one menstrual cycle, contributes to the occurrence of pregnancy in approximately 20% of cases.
And now - in more detail about the “mechanism of conception” at its different stages.
Egg. The “reserve” of eggs is determined already at the birth of a girl; it is about 400 thousand. During one menstrual cycle (from the first day of one menstruation to the first day of the next), one egg, as a rule, matures in one of the ovaries.
After the release of an egg from the ovary (ovulation), which occurs approximately on the 14th day of the menstrual cycle, a corpus luteum. It secretes hormones (gestagens) that prepare the uterus to receive the embryo, and if pregnancy occurs, they maintain the pregnancy. The role of gestagens is especially important in the first trimester of pregnancy. From the ovary, the egg enters the abdominal cavity. Next to each ovary there is an oviduct - a fallopian (uterine) tube, into the funnel of which the egg must enter thanks to the movements of the cilia of the fallopian tube, which “capture” the egg (it itself does not have the ability to move). In 6-7 days, the egg, thanks to contractions of the fallopian tube, must cover a distance of 30-35 cm from the funnel to the uterus. Under ideal conditions, fertilization occurs while the egg is in the upper third of the oviduct.
After ovulation, the egg remains viable for approximately 24 hours.
Sperm. Sperm are formed and mature in the seminiferous tubules of the male reproductive gland - the testes. The process of their maturation lasts on average 74 days. A mature normal human sperm consists of a head, neck, body and tail, or flagellum, which ends in a thin terminal filament. The total length of the sperm is about 50-60 µm (head - 5-6 µm, neck and body - 6-7 µm and tail - 40-50 µm). Thanks to the “beating” of the tail, the sperm is able to move. Interestingly, the size of the egg is much larger than the size of the sperm: it is 0.1 mm. Mature sperm exit from the seminiferous tubules into the vas deferens of the male gonads, where they can retain fertilizing ability for a long time. At this time they are motionless - they acquire the ability to move only during ejaculation.
In the genital tract of a woman, sperm retain the ability to move within 3-4 days, but they can fertilize an egg only within 24 hours. There is an assumption that sperm “recognize” the egg by smell - for example, receptors similar to those found in the nose have been found on the surface of male reproductive cells.
Fertilization- the fusion of a male germ cell (sperm) with a female one (egg), leading to the formation of a zygote (a new single-celled organism). Biological meaning Fertilization consists of the union of paternal and maternal genes. Sex cells contain a so-called haploid (half) set of chromosomes; when they combine, a zygote with a diploid (complete) set of chromosomes is formed.
The seminal fluid entering the vagina usually contains from 60 to 150 million sperm. The speed of sperm movement is 2-3 mm per minute. Thus, already 1-2 minutes after sexual intercourse, sperm reach the uterus, and in 2-3 hours in the female body they can travel 25-35 cm and reach the end sections of the fallopian tubes. After ejaculation (ejaculation), sperm quickly rise through the genital tract due to contractions of the uterus and fallopian tubes; These are so-called peristaltic movements, which are similar to intestinal contractions. Intrinsic sperm motility becomes important in later stages. Sperm, which consists of a biologically active liquid part and sperm, has a slightly alkaline reaction: sperm are capable of active movement only in such an environment. If the environment in the vagina is acidic, then seminal fluid can reduce its acidity to the required level. No more than a few hundred sperm reach the egg: at all stages of their movement, the least viable ones die and are removed. This happens thanks to mechanisms natural selection, that is, the goal (egg) is most often reached by the most complete (without structural defects) sperm.
During the movement of spermatozoa fallopian tube capacitation occurs - a series of changes due to which sperm acquire fertilizing ability. During capacitation, special substances that prevent fertilization are removed from the surface of sperm. (Before the capitation process, these substances perform protective function.) The beating of flagella changes and becomes much faster, which causes overactive motility of spermatozoa. When capacitation has ended and the sperm have reached the site where fertilization is to occur, they undergo the process of acrosome activation. With the help of the acrosome, which is located on the head of the sperm and contains the enzymes necessary for penetration into the female sex cell, they destroy the shell of the egg in the area in front of the sperm, due to which the fusion of male and female reproductive cells occurs. As soon as the first sperm begins to fuse with the egg, its properties immediately change: it becomes immune to other sperm.
After the embryo enters the uterine cavity on the 6-7th day of development, it “hatches” from the membrane, and then the implantation process begins - the half-millimeter embryo attaches to the wall of the uterus and is completely immersed in it in less than two days.
This is how the long journey of “life before birth” begins, 9 months long.
How long can sperm live in a woman’s body and retain fertilizing ability? What happens to sperm that do not reach the egg?
Sperm move independently in seminal fluid. However, it is not known how they behave once they enter the female genital tract: whether they constantly move or sometimes stop moving; whether the substances necessary to restore the energy spent on movement are obtained from the products of the environment in which they live, or together with the seminal fluid. But since we know that sperm stored in an incubator at body temperature and protected from drying out remain alive for more than 8 days and are in constant motion during this period, we can assume that they maintain their mobility throughout the entire time they are present in the female genital tract .
The lifespan of sperm in the body is determined by researchers in different ways. Some authors believe that it is 24-36 hours, others - 8-14 days.
Under a microscope, the speed of movement of a sperm is approximately 3 mm per minute, i.e., in a second it moves the length of its body. When moving, a lot of energy is consumed, since the sperm is forced to overcome
obstacles and move against the flow. And since the ciliated cilia of the female fallopian tubes set the direction of this flow, sperm always move towards the ovary. The capillary nature of this flow naturally reduces their speed. It is believed that in the uterus, sperm travel 1-1.5 cm in 3 minutes, i.e., to leave the seminal mass, enter the uterine pharynx and from there rise into the uterine cavity, the sperm needs approximately 1.5-3 hours. A few hours later, they can be found at the side of the fallopian tube, where they connect to the egg. Only one sperm penetrates the egg, its head fuses with the nucleus, and this fusion, in essence, is fertilization.
If these calculations are considered correct, then fertilization occurs no earlier than 8 hours after sexual intercourse. The question arises: after what period of time can fertilization not occur, unless, of course, there was repeated copulation? The answer is not easy. But the results of observations give reason to believe that this period can be very long. It is possible that a sperm can fertilize an egg even 8-10 days after copulation. Some researchers believe that if sexual intercourse took place before menstruation, sperm can survive in the tube and fertilize the egg after the menstrual period. This hypothesis cannot be rejected unconditionally, especially when it comes to early ovulation. It is currently accepted that sperm can remain motile in the cervical mucus or tube for 7-8 days, but their fertilizing ability remains approximately 24 hours.
What happens to sperm that do not reach the egg? After all, the egg can only accept one sperm and after that it is closed to everyone else. And since with each copulation 200-500 million sperm enter the vagina, it is clear that a countless number of them die. Some sperm leave the vagina along with the sperm that flows out of it. The remaining, also significant, part quickly dies in the vagina under the influence of the high acidity of vaginal discharge. Spermatozoa can live only in moderate acidity, which occurs in the vagina at certain times, as well as in the weak alkaline environment of sperm, uterine mucus, and tubal fluid.
Dead spermatozoa decompose. Their remains flow out of the vagina or are removed by rinsing. On the other hand, their breakdown products, as well as other substances contained in sperm, are absorbed by the vaginal wall and enter the body.
A small part of the sperm enters the uterus and moves towards the tubes, but most of them die along the way. Since the susceptibility of the uterine mucosa to sperm breakdown products is greater than that of the vaginal walls, some sperm penetrate directly into this lining. They were found there between the cells at all stages of decay, and it is clear that in this state they are absorbed even better and replenish the body's juices.
Ultimately, very few sperm make it to the fallopian tubes. And there they all, except one, who fertilizes the egg, die. However, no one noted their presence in the mucous membrane of the tubes. Probably, the remains of dead sperm are carried by capillary flow into the uterus.
Some sperm, which are able to resist longer and have the greatest mobility, sometimes reach the abdominal cavity.
As experiments with the introduction of sperm into the abdominal cavity have shown, there the sperm are devoured by phagocytes (white blood cells), which provide protection to the body, are digested and disappear within approximately twenty hours.
In the seminal fluid, sperm move independently. But it has not been fully studied how they behave when they enter the female reproductive tract. Are they constantly moving or do they stop moving? do they receive necessary substances from the environment in which they live, etc. But it is a known fact that sperm stored in an incubator, which is protected from drying out at body temperature, have a lifespan of more than 8 days.
Sperm maturation time
In the male body, sperm mature in 72 to 74 days. But they live quietly in appendages, hardly move and breathe little. They protect themselves until they enter the female body. If they remain in the male body for a long time, they age and become unsuitable for fertilization.
Lifespan of sperm
The lifespan of sperm in the female body is determined differently by researchers. Some believe that their life is 1-1.5 days, others 8-14 days.
Sperm movement speed
Under a microscope, the movement speed is approximately 3 mm per minute. We can say that it moves the length of its size in a second. Due to the fact that the sperm overcomes obstacles and moves against the current, a large amount of energy is consumed. And since the ciliated cilia of the fallopian tubes set the direction of this flow, the sperm always move towards the ovary. In the uterus, sperm travel 1-1.5 cm in three minutes. A few hours after intercourse, they enter the side of the fallopian tube, and there they connect with the egg. But only one sperm penetrates the egg and fertilizes it.
How long does it take for fertilization to occur?
If the calculations are correct, fertilization occurs no earlier than 8 hours later. But after what time can fertilization not occur if there has been no repeated intimacy? According to research results, fertilization can occur even 10 days after intimacy. Even in some cases, it happens, although very rarely, that if an intimate relationship took place before menstruation, sperm can survive and fertilize an egg even after the menstrual period.
What happens to sperm that has not fertilized an egg?
I wonder what happens to sperm that do not get into the egg, because only one sperm can get into it? Between 200 and 500 million sperm enter the vagina during each sexual intercourse. A small part of them, along with sperm, flows out of the vagina. The remaining part of the sperm in the vagina quickly dies under the influence of the acidity of the vaginal discharge. The fact is that the life of sperm can only exist under moderate acidity, and this acidity occurs in the vagina only at certain moments, also in a slightly alkaline environment of sperm, tubal fluid, and uterine mucus.
As a rule, dead sperm in the female body decompose, and their remains are removed by flowing out or washing. But some of their breakdown products are absorbed into the body by the vaginal wall.
A small part of the sperm still enters the uterus, but the majority die en route. Due to the fact that the uterine mucosa is more susceptible to sperm breakdown substances than the vaginal walls, some sperm directly penetrate this membrane. They were found there at all stages of decay and it is clear that in this state they are absorbed even better, replenishing the body’s juices.
A very small number of sperm ultimately survive to reach the fallopian tubes. And it is there that they all, except one, connecting with the egg, die. A certain number of sperm, which are able to resist the environment longer and have greater mobility, reach the abdominal cavity. But according to the results of experiments with the introduction of sperm into the abdominal cavity, sperm there are destroyed by phagocytes (white blood cells) and disappear in approximately less than a day.
What affects the lifespan of sperm?
The lifespan of sperm is an individual indicator that is influenced by various factors. For example, if sperm is enriched with fructose, then their lifespan will be longer. Fructose is a source of energy for sperm. Drinking alcohol can reduce their life expectancy medicines, inflammatory diseases etc.
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