Fertilization is the joining of sperm and egg in the form of afertilized egg.
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Fertilization is the joining of sperm and egg in the form of afertilized egg.The cell contains genetic information from both parents. This is the first step in development.embryoThis article will explain in detail the mechanisms involved in the fertilization process.
what we cover
What is insemination?
gamete
fertilization stage
(1)Training (preparation)
(2)acrosome reaction (interaction)
(3)fusion
time of fertilization
What is insemination?
We need two cells to complete the fertilization process. We need sperm from the male reproductive system, specifically from the testicles. We also need an egg (so-calledegg) of the female reproductive system, in particularovaryThese two cells, sperm and egg, fuse and merge into one cell, the so-calledfertilized egg.This fertilized egg becomes the firstembryo(become a baby). A fertilized egg contains genetic information from the sperm and the egg.(1, 2)
In this article, we will explain the process and mechanism of fertilization in more detail.
Gametes: What makes sperm and eggs so special?
Sperm is produced by the male reproductive system. ovules (pluralegg, also known as ova) are produced by the female reproductive system. These cells are calledgameteThey are highly specialized in reproduction, which is necessary to create new organisms (new people!).
sperm
The male reproductive system produces sperm in the testicles. These units are very small and modern. They have a long tail called a whip that propels them forward. This allows them to travel exclusively through the female reproductive tract to the egg. Sperm generate a lot of energy to move forward. The genetic material necessary for fertilization is found only in the sperm head. The rest of the sperm is used for motility.(3, 4)
ovum
Oocytes, also known as egg cells, are female reproductive cells specifically designed to develop into a fetus. ova stored inovary.Each month, an egg is released in one of theoviductperiodovulation.If you want to know more about the monthly menstrual cycle, you can read ithere.If you want to know more about the biology of the ovum, you can consultthis article.
Unlike sperm, the ovum is a large cell. In fact, it is the largest in the human body! This is very important because eggs need to store many nutrients and proteins needed for growth and development.embryoneed. In addition, the ovulated egg is surrounded by a protective layer calledtransparent areaThe zona pellucida prevents more sperm from fertilizing the egg. It ensures that only one sperm penetrates the hair and is fertilizedegg.(3, 4)
What are gametes?
Although sperm and eggs look different, they share a very important characteristic that is crucial to their ability to reproduce. they are allgameteand it contains only half the amountdecalcified nucleosaccharide nucleic acidcompared to other cells in the human body. Our DNA is a molecule that containsGenthey carry our genetic information. Our bodies need this information to know what to do. Because gametes contain only half of their DNA, they are calledhaploidcell. Cells that contain "all" DNA are calleddiploidcell. Almost all cells in your body that are not gametes are diploid.(4, 5)
When sperm and eggs come together during fertilization,fertilized eggHalf of your DNA comes from the egg and the other half from the sperm. That way you get a "complete" set of DNA, which becomes adiploidcell. This characteristic of gametes and fertilization explains why children inherit traits from both parents.(4, 6)
This image shows gametes (a), sperm and egg cells joining and fusing (b) to form a fertilized egg (c). The middle picture (b) shows that only one sperm can break through the egg's protective shell. The zygote contains all the DNA of the egg and sperm. Images courtesy of Lea Dörner.
fertilization stage
Now that we understand the unique characteristics of sperm and egg, let's talk about the actual process of fertilization and what happens when the sperm and egg "meet."
Fertilization can be divided into 3 phases: capacitation, acrosome reaction and fusion, all of which we will explain below.
Training: sperm preparation
During unprotected intercourse between a person with a vagina and a person with a penis, millions of sperm are released into the vagina. From that moment on, the sperm begins its journey through the vaginal patient's reproductive tract. swim throughcervix, according toUterus, then enteroviduct.Once a month, duringovulation, ovum ofovaryenters one of the fallopian tubes(7).
The ovum in the fallopian tube is the "target" of the sperm. They are guided to their destination by molecules secreted by the egg.(8)This journey is necessary for fertilization. Only the fastest sperm can fertilize an egg. But after ejaculation, the sperm cannot fertilize the egg even if it reaches the egg immediately. During its passage through the reproductive tract, the vaginal environment affects sperm in several ways. It is calledAbilitiesThe process involves chemical changes caused by small molecules, proteins and vaginal acid levels. The end result is a sperm that can fertilize an egg.
In short, capacitation can be described as the activation of sperm by the vaginal environment. Then the sperm and egg meet.(1, 3)
Acrosome reaction: interaction of sperm and egg
Of the 300 million sperm ejaculated during intercourse, only about 200 reach their destination:egg(ova). The sperm that managed to reach the egg must now make its way to the so-calledtransparent area, which surrounds the egg. The sperm's response to cross this barrier is calledacrosome reactionWe explain how it works.
When the sperm meets the egg, it attaches to the surface of the egg:transparent areaThe zona pellucida is a protective layer that surrounds the ovum. It consists of special proteins. This layer is very important during fertilization.(9)For example, it acts as a barrier between different animal species. This means, for example, that hamster sperm cannot fertilize human eggs.
When the sperm reaches the zona pellucida, the sperm head releases a substance calledacrosome.This substance containsheavy(special protein) helps the penetration of spermtransparent areaGet to the egg Akros can be considered the "key" to the "door" of the zona pellucida.
After the sperm has reacted with the zona pellucida, the zona layer "blocks" all other sperm behind it. Because of this, usually only the first sperm that reaches the egg can fertilize it. Sperm that fail to fertilize an egg simply disintegrate. Eventually, they are naturally excreted from the body. Now the fastest sperm is ready to connect with the egg!(1, 2, 4, 9, 10)
fusion of sperm and egg
After the sperm sufferedacrosomereact and penetratetransparent area, which can be combined with eggs. Both cells are surrounded by a thin layer of proteins calledmembraneThese membranes open slightly to allow the mixing of sperm and egg contents. During mating, the entire contents of the sperm are drawn into the egg. Two cells merge into one cell, the so-calledfertilized egg.The fertilized egg contains a combinationdecalcified nucleosaccharide nucleic acid(gene) sperm and eggs, the first cells in developmentembryo.After fertilization, the fertilized egg descendsoviductand they begin to divide and multiply, eventually implanting in the wall of the uterus. This is where the embryo can grow bigger and bigger until it is born as a baby.(4, 11)
time of fertilization
Time is an important factor when it comes to fertilization. fertile window, or a person suffering fromUteruscan you get pregnant on your owndays in each menstrual cycle.This is because when the egg is insideovulation, has a short lifespan and is doomed to die in a few hours or days if not fertilized.
On the other hand, spermatozoa can survive up to five days inside the female reproductive system. This means that if someoneovulationSperm capable of fertilizing an egg and resulting in pregnancy within five days of unprotected vaginal intercourse with a man or person with a penis.(4, 12).
Remember, anyone with the right part can get pregnant! If you have testicles and a penis, you can get pregnant with a vagina,Uterusgovary, even if they were taking sex-enhancing hormones, such as testosterone.
In conclusion, sperm must travel a long way and go through many changes before fertilizing an egg. The egg is protected by a special coating from all these sperm. Only the fastest sperm that can pass through this layer can connect with the egg. The result is a cell,fertilized egg, which contains all the nutritional and genetic information carried by sperm and eggs. The miracle of life begins small!
From there, the fertilized eggs can develop intoembryo, Then afetus, and finally he was born as a baby.
reference
Gupta SK. The role of zona pellucida glycoproteins in human fertilization.Journal of Reproductive Immunology. 2015；108：90-7。 DOI: 10.1016/j.jri.2014.08.006
Georgadaki K, Khoury N, Spandidos DA, Zoumpourlis V. Molecular basis of fertilization (review).International Journal of Molecular Medicine2016;38(4):979-86. DOI: 10.3892/ijmm.2016.2723
Georgadaki K, Khoury N, Spandidos DA, Zoumpourlis V. Molecular basis of fertilization (review). International Journal of Molecular Medicine. 2016;38(4):979-86. DOI: 10.3892/ijmm.2016.2723
Alberts B, Johnson A, Lewis J, Raff M, Roberts K i Walter P.molecular cell biology.4. edition. Oxford University Press, 2003.
Jacobs, Pennsylvania. Chromosome complement of human gametes.Oxford Review of Reproductive Biology. 1992.; 14: 47-72.
Tosti E, Boni R. Electrical events during gamete maturation and fertilization in animals and humans.Human reproduction update. 2004.; 10 (1): 53-65. DOI: 10.1093/humupd/dmh006
Holesh JE, Bass AN, Lord M. Physiology, ovulation. exist:brilliant statisticsStatPearls Press, Treasure Island (FL), 2022.
Contreras HR, Plains, MN. Detection of progesterone receptor in human spermatozoa and its correlation with morphological and functional properties.International Journal of Andrology. 2001.; 24 (4): 246-52. DOI: 10.1046/j.1365-2605.2001.00294.x
green PD. Three-dimensional structure of the zona pellucida.copy the comment. 1997.; 2: 147-56. DOI: 10.1530/revreprod/2.3.147
Evans J.P. Molecular basis of sperm and egg membrane interactions during mammalian fertilization.Human reproduction update. 2002；8(4):297-311。 DOI：10.1093/humupd/8.4.297
Deneke VE, Pauli A. The mystery of fertilization: how sperm and egg unite.Annual Review of Cell and Developmental Biology. 2021.; 37: 391-414. DOI: 10.1146/annurev-cellbio-120219-021751
(Video) from fertilization to childbirth | 3d medical animation | by Dandelion TeamWilcox AJ, Dunson D, Baird DD. The timing of the "fertile window" in the menstrual cycle: date-specific estimates from a prospective study.British Medical Journal. 2000；321(7271):1259-62。 DOI: 10.1136/bmj.321.7271.1259
Keep in mind:The information we provide here is for educational purposes only. If you feel any discomfort or have any complaints or questions about your health, please contact your doctor or other relevant health professional. We do not provide medical advice.
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FAQs
What happens when egg and sperm meet? ›
Contact between the egg and sperm is random. Once the egg arrives at a specific portion of the tube, called the ampullar-isthmic junction, it rests for another 30 hours. Fertilization — sperm union with the egg — occurs in this portion of the tube. The fertilized egg then begins a rapid descent to the uterus.
Does your body know when fertilization happens? ›You won't feel when an egg gets fertilized. You also won't feel pregnant after two or three days. But some women can feel implantation, the process in which the fertilized egg travels down the fallopian tube and buries itself deep within the wall of the uterus.
What happens when a sperm and egg meet describe the process of fertilization and early stages of the zygote and embryo? ›During fertilization, the sperm and egg unite in one of the fallopian tubes to form a zygote. Then the zygote travels down the fallopian tube, where it becomes a morula. Once it reaches the uterus, the morula becomes a blastocyst. The blastocyst then burrows into the uterine lining — a process called implantation.
How do I know if I am fertile enough to get pregnant? ›If your menstrual cycle lasts 28 days and your period arrives like clockwork, it's likely that you'll ovulate on day 14. That's halfway through your cycle. Your fertile window begins on day 10. You're more likely to get pregnant if you have sex at least every other day between days 10 and 14 of a 28-day cycle.
How does your body feel after sperm enters? ›Signs Sperm Has Entered the Body
Pregnancy symptoms such as delayed periods, fatigue, morning sickness or even implantation cramps are a few signs that confirm the sperm did go inside.
Once the sperm enters the reproductive system, it can take about 30-45 minutes to reach the egg. For this, it is important to have a healthy sperm which has the right kind of motility to reach the egg and fertilize it. Once inside the body of a woman, a healthy sperm can live up to 2-5 days.
What happens to your body right after fertilization? ›After conception, a fertilized egg travels through your fallopian tubes to your uterus. The fertilized egg (called an embryo) implants (attaches) into the wall of your uterus. This triggers the placenta to form. Your placenta begins producing and releasing human chorionic gonadotropin (hCG) into your blood and pee.
How does one feel immediately after fertilization? ›Early signs and symptoms include implantation bleeding or cramps, which can occur 5–6 days after the sperm fertilizes the egg. Other early symptoms include breast tenderness and mood changes.
What happens immediately after egg is fertilized? ›After fertilisation, the egg and sperm very quickly merge and divide to become an embryo and chemicals are released to stop other sperm from entering. Over the next four or five days the fertilised egg continues to divide and to travel towards the uterus.
What are the 4 steps of fertilization? ›The stages of fertilization can be divided into four processes: 1) sperm preparation, 2) sperm-egg recognition and binding, 3) sperm-egg fusion and 4) fusion of sperm and egg pronuclei and activation of the zygote.
What happens before an egg is ready to be fertilized by sperm? ›
What Happens During Fertilization? Before sperm can fertilize an egg, they need to be “prepped” through a process known as capacitation. During capacitation, the sperm undergo changes from fluids in the female reproductive tract, which helps them to penetrate the egg.
How do I know if ovulation has passed? ›As you get close to ovulation, your cervical mucus will become copious, clear and slippery—like egg whites. It stretches between your fingers. Once your discharge becomes scant and sticky again, ovulation is over.
What are the symptoms of high fertility? ›These can include abdominal pain or cramps, bloating, slightly elevated body temperature, changes in cervical mucus and saliva, and breast tenderness. Ovulation is a part of your fertile window, but pregnancy can happen up to 5 days prior and 1 day after you've ovulated.
Why am I not getting pregnant during my fertile window? ›Some common reasons include stress, not timing baby-making sex with ovulation, residual effects of hormonal birth control, and certain health conditions. As much as we may try, pregnancy really can't really be planned—but you can increase your chances by being aware of common pitfalls.
What are the chances of sperm meeting egg? ›-For the nearly 5,000 sperm that make it into the utero-tubal junction, around 1,000 of these reach the inside of the Fallopian tube. -For the 1,000 sperm entering the tube, only around 200 actually reach the egg. -In the end, only 1 lucky sperm out of this group of 200 actually penetrates and fertilizes the egg!
How long does it take for sperm to enter your body? ›Usually, the sperm reaches the egg within 15 to 45 minutes of ejaculation. However, the process could be much longer than that if you haven't ovulated yet by the time you have sex, because sperm can live inside a reproductive tract and wait for an egg for up to five days.
Where does dead sperm go in the female body? ›Unless one deposits sperm into a woman's reproductive tract, it lives out in the open for only a few minutes. However, sperm can live inside the body of a woman for about 3-5 days. If, for whatever reason, the sperm is not able to fertilize the egg, that dead sperm moves towards the uterus and disintegrates.
How many drops of sperm is needed to get pregnant? ›How many sperm do you need to get pregnant? It takes just one sperm to fertilize a woman's egg. Keep in mind, though, for each sperm that reaches the egg, there are millions that don't. On average, each time men ejaculate they release nearly 100 million sperm.
How does your stomach feel after fertilization? ›The sensation is different from person to person, but in most cases, they feel like mild cramps, usually dull and aching, or light twinges. Some people also describe feeling a prickling, tingling, or pulling sensation. The sensations may come and go or last for one to two days before disappearing.
What not to do during implantation? ›It's recommended that you avoid strenuous physical activities like heavy weight-lifting or high-impact cardio during your two-week wait as it could lead to uterine contractions and affect the implantation process. After the first few days of our waiting period, you can do some light exercising like walking or swimming.
How soon after fertilization do you feel tired? ›
Pregnancy fatigue can start as soon as one week after conception, which means it may be an early sign of pregnancy before a test can tell you for sure. It's also common to start feeling tired any time during the first 12 weeks.
Can you feel fertilization the next day? ›How early do pregnancy symptoms start? It varies. Some people feel pregnant within a few days of conception, while other people don't feel pregnant for weeks after a positive pregnancy test. Pregnancy symptoms vary between people and even between pregnancies.
How long after fertilization do you get a positive? ›In many cases, you might get a positive result from an at-home test as early as 10 days after conception. For a more accurate result, wait until after you've missed your period to take a test. Remember, if you take a test too soon, it could be negative even if you're pregnant.
What percent of sperm live 5 days? ›Sperm would have a 5% probability of surviving more than 4.4 days and a 1% probability of surviving more than 6.8 days.
How can I increase my chances of implantation? ›- Change Your Diet. Numerous scientific studies have shown that good nutrition is key for fertility and successful implantation. ...
- Avoid Anti-Inflammatories. ...
- Reduce Your Caffeine Intake. ...
- Avoid Stress. ...
- Exercise Regularly. ...
- Be Positive. ...
- Increased Sexual Intercourse.
Failed Implantation Symptoms
Generally, when implantation occurs, you may experience sensitive breasts and mild abdominal cramping. If you haven't experienced these in the weeks after your embryo transfer, it may be indicative that the implantation has failed. Additionally, you may experience vaginal bleeding.
The fertilized egg stays in the fallopian tube for about 3 to 4 days. But within 24 hours of being fertilized, it starts dividing fast into many cells.
What are 3 causes of high fertility rates? ›- The mother's preference of family size, which influences that of the children through early adulthood. ...
- Social pressure from kin and friends to have another child.
- Social support. ...
- Happiness, with happier people tending to want more children.
- A secure housing situation.
The three primary signs of fertility are basal body temperature (BBT), cervical mucus, and cervical position.
Why am I not getting pregnant but everything is fine? ›Dr Priti explained, “An unhealthy lifestyle, weight issues, high stress and confusion about the fertile period could be possible reasons for not getting pregnant.”
How can a woman become more fertile? ›
- Maintain a healthy weight. Being overweight or significantly underweight can inhibit normal ovulation.
- Prevent sexually transmitted infections. Infections such as chlamydia and gonorrhea are a leading cause of infertility for women.
- Avoid the night shift, if possible.
Your chances of getting pregnant in any given month are about 20-25%. Within two years, 95% of people trying to achieve pregnancy, who do not have infertility issues, will succeed. The SMEP plan tries to better those odds by ensuring that the sperm meets the egg during each cycle.
How long does it take after conception to become pregnant? ›Pregnancy doesn't start the day you have sex — It actually takes up to 2-3 weeks after sex to become officially pregnant. It can take up to 6 days after sex for the sperm and egg to join — if a sperm cell joins with an egg, it's called fertilization.
What happens to the sperm when a woman is already pregnant? ›Most of it will simply be discharged from the body through the vaginal opening. Thanks to the placenta, amniotic sac, and mucus plug covering the cervix, your baby has a protection system that's very specific about what goes in and stays out!
Can the egg reject a sperm? ›Researchers from Stockholm University and the Manchester University NHS Foundation Trust found that the egg effectively chooses the sperm it wants, and rejects the others. "Human eggs release chemicals called chemoattractants that attract sperm to unfertilised eggs.
How long does it take for a sperm and egg to connect? ›The Fertilization Process
The actual estimated time that it takes for the sperm to travel to the egg and fertilize is around six days after intercourse. Once it becomes fertilized, the egg will attach itself to the uterine wall, which can take anywhere between six and ten days.
Only one sperm needs to survive in order to fertilize an egg. However, the journey from the man's testicle to the woman's uterus is long and arduous. After ejaculation, a single sperm cell measuring only 0.5 mm needs to swim over 152 mm from the base of the cervix to the egg for fertilization.
How can I tell what day I conceived? ›The best way to determine your conception date is with a pregnancy confirmation ultrasound. Early pregnancy ultrasounds can determine the age of your growing baby and when you likely conceived.
How many times should a man release sperm in a week? ›Some studies suggest that moderate ejaculation (2–4 times per week) is associated with a lower prostate cancer risk. However, ejaculating more often doesn't mean your cancer risk drops even more.
Can the second release of sperm make you pregnant? ›The next time you have sex, the number of sperms is not as much as the first time, but the quality of sperm remains stable, and that quantity is enough for fertilization to occur. This proves that having sex twice in a row is still possible to get pregnant if there is no reasonable protection.
What happens if I sleep with another man while pregnant? ›
You can have sex with a new partner now you're pregnant. Having sex with someone else won't harm your baby.