egg cells travel down the

An official website of the United States government

The .gov means it's official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings
• Browse Titles

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-.

InformedHealth.org [Internet].

In brief: how does the menstrual cycle work.

Last Update: April 25, 2022 ; Next update: 2025.

It is thought that all of the egg cells a woman will ever have are already inside her ovaries when she is born. These egg cells lie in small pockets called follicles. Once puberty starts, different hormones cause the first follicle to mature and release an egg cell (ovum).

Hormones are substances produced by the body that act as chemical messengers. They regulate body functions like the menstrual cycle and body temperature . Hormones also trigger ovulation.

• What happens during ovulation?

Women can get pregnant around the time a mature egg cell has left their ovary. The egg cell travels down the fallopian tube into the womb (uterus). The moment the egg cell leaves the ovary is called ovulation. Once a girl has had her first monthly period, ovulation usually occurs once a month.

Female sex organs

• What happens during a menstrual period?

During the monthly hormone cycle, the mucous membranes lining the inside of the womb prepare for a possible pregnancy. The lining becomes thicker so that a fertilized egg can settle in the womb and be supplied with nutrients for a baby to grow . If the egg cell is not fertilized, it dies.

At the end of the cycle, some blood vessels in the mucous membranes of the womb open up for some time, and the uppermost mucous layer detaches. In order to shed this layer, the muscles of the womb tighten and relax in an irregular rhythm. That allows the tissue to break away from the wall of the womb and leave the body through the vagina, together with some blood . This is the monthly period, also called menstruation. As long as a woman is not pregnant and is not using hormonal contraceptives, the period is usually a sign that one menstrual cycle has finished and the next one has started. A period usually lasts between three to seven days in most women.

Even though menstrual fluid may look like a lot when it is on a pad or in a tampon or menstrual cup, normally only about 20 to 60 ml of blood are shed during the monthly period: that is only about 4 to 12 teaspoons.

Most women begin to have irregular periods as they approach menopause. Their periods then stop completely at the age of 51 on average. A woman is said to have reached menopause when she hasn't had a period for one year. The time leading up to the last period is known as the menopause transition or perimenopause. A likely deciding factor for when menopause will occur is the number of follicles remaining in the ovaries. Until around the age of 40, the number of follicles drops slowly. After that, the number drops quite quickly, until no more follicles mature.

• Brandes R, Lang F, Schmidt R. Physiologie des Menschen: mit Pathophysiologie. Berlin: Springer; 2019.
• Menche N. Biologie Anatomie Physiologie. München: Urban und Fischer; 2016.
• Pschyrembel Online . 2022.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

• Cite this Page InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. In brief: How does the menstrual cycle work? [Updated 2022 Apr 25].

In this Page

Informed health links, recent activity.

• In brief: How does the menstrual cycle work? - InformedHealth.org In brief: How does the menstrual cycle work? - InformedHealth.org

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

Connect with NLM

National Library of Medicine 8600 Rockville Pike Bethesda, MD 20894

Web Policies FOIA HHS Vulnerability Disclosure

Help Accessibility Careers

• Ovulation and conception
• Single and lesbian women
• Optimising conception

Every month, the reproductive organs in a healthy woman prepare for pregnancy.

A complex interaction between the pituitary gland in the brain, the ovaries and the uterus work to create the perfect environment for ovulation (the release of an egg) to occur, for the sperm and egg to meet and for the fertilised egg to implant itself in the uterus.

A step-by-step guide to ovulation 

• Every month the pituitary gland, which is in your brain, releases a hormone. This hormone tells the ovaries to produce a number of fluid-filled cysts called follicles. As the follicles grow they secrete the hormone oestrogen. Oestrogen works to thicken the wall of your uterus in preparation for pregnancy.
• On day seven of your cycle, the follicles stop growing except for one. This follicle continues to grow and to nourish a maturing egg (oocyte) within.
• On day 12 the maturing follicle releases a burst of oestrogen into the blood stream. The oestrogen travels through your blood.  When the oestrogen reaches the pituitary gland in your brain, the pituitary gland responds by releasing the luteinising hormone. This hormone gives the follicle a sudden growth spurt.
• Right before ovulation, the egg inside the follicle detaches itself. The follicle starts to release chemicals that encourage the nearby fallopian tube to move closer and surround the follicle.
• The follicle swells until it bursts open, ejecting the egg and fluid into the abdominal cavity.
• Small finger like protrusions at the end of the fallopian tube, called fimbriae, sweep across the burst follicle and pick up the egg.
• The egg is transported to the entrance of the fallopian tube. Once inside the walls of the fallopian tube, muscle contractions push the egg gently towards the uterus.
• The egg will either meet sperm on its journey through the fallopian tube and fertilisation will happen, or it will arrive in the uterus unfertilised and be absorbed back into the body.

The menstrual cycle

A step-by-step guide to conception 

After ovulation the egg lives for 12 to 24 hours and must be fertilised in that time if a woman is to become pregnant.

The burst of oestrogen just before ovulation also works inside the neck of the uterus (the cervix) to make protein-rich clear jelly that covers the top of the vagina during sex. This makes the vagina acidic (which prevents thrush and other infections). This is also a suitable environment for sperm survival. The sperm rapidly swim up and into the cervix, where they can survive in the mucus for up to five days before an egg is released.

When the egg is released at ovulation, it is covered in sticky cells, which help the fallopian tube to catch it. The egg and the sperm meet in the fallopian tube where the sperm start to digest the sticky cells. While it takes only one sperm to make a baby, several need to attach to the outer shell and the membrane of the egg before one can enter and fertilise it.

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.

The hormone progesterone, which is secreted into your blood stream by the burst follicle (now called the corpus luteum) prepares the uterus for the egg to implant.

As the pregnancy grows and implants itself into the mother’s uterine lining and blood vessels, it is sending an increasingly strong signal to the ovary to prolong and increase its production of progesterone, which the pregnancy needs to survive.

Getting pregnant

The best time to attempt a pregnancy is in the three to six day leading up to and including ovulation. The most fertile days will vary depending on your cycle length.

If you are using contraception you will need to stop using it if you plan to get pregnant. There are no clear guidelines about when to stop using the Pill (oral contraception) if you are planning to get pregnant. Some health professionals suggest you have three normal menstrual periods, after stopping the Pill, to allow your metabolic function to return to normal. The length of time that it takes for fertility to return will differ for each woman. It is possible, although rare, for a woman to fall pregnant while on the Pill. There is no evidence that this causes problems for the baby.

Related information

• See also: Preparing for pregnancy for things to consider before you get pregnant
• Provide feedback about the content on this page

The Women’s does not accept any liability to any person for the information or advice (or use of such information or advice) which is provided on the Website or incorporated into it by reference. The Women’s provide this information on the understanding that all persons accessing it take responsibility for assessing its relevance and accuracy. Women are encouraged to discuss their health needs with a health practitioner. If you have concerns about your health, you should seek advice from your health care provider or if you require urgent care you should go to the nearest Emergency Dept.

How sperm meets egg: a journey from production to fertilization

Many wonder what the sperm ´s journey is like from ejaculation to fertilization. The ultimate goal of a sperm is to fertilize the egg cell.

However, the journey of the sperm to get to the egg is not an easy one. To reach the egg cell, the sperm has to go through a long and difficult journey that can take from thirty minutes to several hours .

For this reason, fertilization needs a large number of motile spermatozoa for at least one of them to be able to overcome all barriers. Firstly for the sperm to get to the egg, and then to fertilize the egg.

Provided below is an index with the 7 points we are going to expand on in this article.

• 1. How the sperm meets the egg
• 2. Route from the testicle to the urethra
• 2.1. Changes in the sperm
• 3. The journey through the female reproductive system
• 3.1. What barriers do spermatozoa have to cross?
• 3.2. The sperm´s arrival at the Fallopian tubes.
• 3.3. Final stage of the spermatozoon: acrosome reaction
• 4. FAQs from users
• 4.1. How long does it take from sperm production to ejaculation?
• 4.2. How can ovulation be calculated so that the sperm and egg meet?
• 4.3. How long can a sperm live in the female reproductive tract?
• 4.4. How many sperm make it to the egg?
• 4.5. How long does it take sperm to reach the egg?
• 4.6. After sperm meets egg, how long until implantation?
• 4.7. Where do the sperm cells pass through on their way to the egg?
• 4.8. Where does the sperm need to get to, to be able to fertilize the egg?
• 5. Recommended reading
• 6. References
• 7. Authors and contributors

How the sperm meets the egg

Colloquially,the path to fertilization we understand as a race in which only the best sperm will be able to reach the finish line and win the prize. Effectively, it is something like this: many spermatozoa start the race, but only one will fertilize the egg.

The route of the sperm to the egg can be divided into two major stages:

• Male reproductive system: the journey of sperm in the male body is from the testicles to the outside world.
• Female reproductive system: from the vagina, where semen is deposited, to the Fallopian tubes, where the egg is found.

It should not be forgotten that during these two phases of the journey the sperm meet certain obstacles. To follow, we discuss what they are.

Route from the testicle to the urethra

It takes about 90 days for spermatozoa to develop and acquire the necessary maturation before they can be expelled in an ejaculation.The birth of spermatozoa takes place in the seminiferous tubules of the testes. They subsequently pass to the epididymis.

The seminiferous tubules are the internal structures of the testicle where sperm are made. The epididymis is a long structure that connects the testicle and the vas deferens.

At the moment of intercourse, a large quantity of sperm (about 250 million) leave the epididymis and pass through the vas deferens and the urethra. Along the way, the sperm are bathed in fluids released from the seminal vesicles and the prostate. In this way, the semen, the mix of sperm and fluids, is formed.

The main function of these seminal fluids is to make is possible for the sperm to enter into the vagina. Sperm will shoot out of the urethra through the penis until they enter the female reproductive tract , specifically the vagina.

Changes in the sperm

During this journey from the testicle to the outside, the sperm acquire the correct shape and structure to allow fertilization of the egg. The changes that occur at this final stage of sperm maturation are:

• DNA compaction to allow the head (where the DNA is stored) to be as small as possible and therefore move better. This also helps it to pass through the zona pellucida (egg shell).
• The tail acquires the perfect design so the sperm have great speed and resistance.
• The middle piece has a large number of mitochondria for high energy production. This gives the spermatozoon great efficiency in energy usage.

If you wish to continue reading information about what the spermatozoon cell is like, we suggest you visit this article: How are spermatazoa formed

The journey through the female reproductive system

In the process of ejaculation, sperm cells leave the man and enter the vagina. This is where the sperm cells begin the second part of their journey to fertilization.

During this second part of the journey the sperm again encounter an large number of obstacles. These obstacles and barriers can hinder the sperms arrival at the Fallopian tubes, where the egg is waiting.

There is a distance of between 15 and 18 cm and time is of the essence. Sperm cannot afford to delay, since the egg, once it has left the ovary (i.e., after ovulation ), has a half-life of about 24 hours. The survival time of the egg is short compared to that of the sperm. Sperm can live between 2 and 5 days in the female reproductive tract.

After ejaculation, the race of the sperm cells begins. It is a race not only of speed but also of endurance . Defective sperm and/or those with poor motility will fall by the wayside.

What barriers do spermatozoa have to cross?

Some obstacles, or barriers, encountered by sperm are as follows:

However, it is not all difficulties in the journey of the sperm. The egg tries to pave the way for the sperm by releasing molecules and sending signals. The fallopian tubes and uterus exert a suction force through rhythmic contractions and the cervical mucus becomes less dense allowing the sperm to swim better.

For its part, the seminal fluid that accompanies the sperm neutralizes the pH and provides sugars to the sperm. This fluid also serves as a protective shield against the woman´s white blood cells.

The sperm´s arrival at the Fallopian tubes.

Once the vaginal, cervical and uterine barriers have been overcome, we encounter the narrowest part of the course: the uterotubal junction . Only a few thousand of the average 250 million spermatozoa in freshly ejaculated semen reach this point.

Along the way, the strongest spermatozoa, i.e. those that have been able to overcome the female obstacles, acquire an extraordinary ability: the ability to fertilize . This is known as sperm hyperactivation . From this moment on, its tail moves with much more force and energy, allowing a vigorous movement that helps it arrive at the egg.

Once they reach the fallopian tubes, many sperm remain attached to the tube walls, exhausted and unable to continue their journey.

At this point, few sperm are left in the race, as the vast majority have been lost along the way. Of the few dozen sperm that remain before the egg's watchful eye, only one will make it through the thick doorway to the egg: the zona pellucida.

The chosen sperm, the strongest and most capable one, upon contact with the zona pellucida, initiates the so-called acrosome reaction .

Final stage of the spermatozoon: acrosome reaction

As mentioned above, when the most able sperm has reached the egg, the acrosome reaction takes place. This is the release of the contents of the acrosome, which is composed of a series of enzymes. The purpose of this enzymatic release is to weaken the zona pellucida of the ovum and facilitate penetration.

The acrosome is a structure located in the head of the sperm. It serves as a reservoir for enzymes and other substances that the sperm needs to pass through the zona pellucida.

This reaction "wakes up" the egg, which releases cortical granules , organelles that prevent any other sperm from penetrating. It is as if the ovum plants a flag indicating to the rest of the spermatozoa around it that it has already been conquered by the winning spermatozoa and, therefore, that the doors of its kingdom are closed.

Once the sperm penetrates the oocyte, their two nuclei fuse. This is what we know as fertilization . If you want to know the details about how the sperm enters the egg and how the new being is formed, you can read this article: The steps of fertilization in humans.

We're already 773!

Join our inviTRA community

FAQs from users

How long does it take from sperm production to ejaculation.

Spermatogenesis is the process whereby male reproductive cells are formed, from the immature ones, spermatogonia, until the mature ones, spermatozoa. This complicated process occurs within the seminiferous tubule in the testis and takes about 64-72 days.

Once spermatozoa (sperm cells) have been produced, they leave the testis and travel to the epididymis, where they will acquire the necessary motility in a process that lasts 10 days approximately. Spermatozoa will be stored in the epididymis until they are expelled with ejaculation. When ejaculation starts, sperm travel through the vas deferends and mixes with the seminal fluid that originates in the secretory glands, creating what we all know as semen . Finally, it is expelled through the urethra.

How can ovulation be calculated so that the sperm and egg meet?

It can be calculated by measuring the daily basal temperature and by performing a urine LH test.

How long can a sperm live in the female reproductive tract?

Once ejaculation occurs and the sperm are released into the vagina, they have a half-life of 2 to 5 days. The stronger ones will survive longer. The weaker ones will die on the way. After fertilization, the dead spermatozoa and the live ones that have remained unable to fertilize the egg will be eliminated by phagocytosis (the body's own system of neutralization and elimination of substances).

How many sperm make it to the egg?

To answer this question, we will split the answer into various figures, each one corresponding to a stage in the journey:

• There are approximately 200-250 million sperm in each ejaculation, but only about 2 million make it to the cervix.
• Once there, out of the 2 million sperm entering the cervix, only about 1 million are able to make it to the uterus.
• Out of the 1 million that enter the uterus, only 10,000 are able to travel to the top of this organ.
• Out of the 10,000 that survive at this point, only half of them travel in the right direction, that is, toward the egg cell.
• Out of the approximately 5,000 sperm that enter the utero-tubal junction, about 1,000 get inside the Fallopian tube.
• Finally, out of the 1,000 that enter the tube, it is estimated that only 200 make it to the egg.

However, in the end, only 1 sperm out of the 200 that reach the egg is able to penetrate and fertilize it.

How long does it take sperm to reach the egg?

There is no set time, since the spermatozoa with the best quality, that is, with great ability to overcome obstacles and great strength of movement, will be able to reach the egg in just half an hour. However, there will be others that will need about two days to cross the entire female reproductive tract.

After sperm meets egg, how long until implantation?

Implantation occurs approximately within 3-7 days after fertilization, as the fertilized egg cell has to travel from the point where it was fertilized to the point where it implants. It depends on how high the point where they meet in the Fallopian tube is. For instance, if they meet high in the tube, it will take about 7 days.

Related stories: What Are the First Signs & Symptoms of Embryo Implantation?

Where do the sperm cells pass through on their way to the egg?

As mentioned above, they must first pass through the male reproductive tract and then, after ejaculation, through the female reproductive tract. In the first part of the journey, they leave the testicle and pass through the epididymis, the vas deferens and the urethra. During this part, they are impregnated with secretions from the prostate and seminal vesicle.

In the second part of the course, the spermatozoa pass from the vagina, where they are deposited, to the cervix. Subsequently, they pass through the uterus and reach the fallopian tubes, where the egg is found or where they wait for it to arrive, in case ovulation has not yet occurred.

Where does the sperm need to get to, to be able to fertilize the egg?

The sperm has to reach the fallopian tubes, where the egg is waiting. Once there, it will be able to fuse with it and give rise to the embryo. Subsequently, the embryo will leave the fallopian tubes, reach the uterus and implant in the endometrium of the uterine cavity. This is the beginning of pregnancy.

Recommended reading

The final goal of this whole journey of the sperm is to meet the egg, fuse with it and allow the birth of a new cell. This cell, after about nine months of successive divisions and processes of differentiation and specialization, will give rise to the future baby.

If you want to know more information about what happens after fertilization, we recommend reading this article: Pregnancy stages month by month

If you are interested in knowing more about the hormones responsible for sperm formation, you can visit this link: Male hormone check .

We make a great effort to provide you with the highest quality information.

🙏 Please share this article if you liked it. 💜💜 You help us continue!

Austin CR. Observations on the penetration of the sperm in the mammalian egg. Aust J Sci Res B. 1951;4(4):581–596.

Bennett M. Shapiro. The existential decision of a sperm, Cell 49, no. 3 (May 1987): 293-94, esp. 293.

Chang MC. Fertilizing capacity of spermatozoa deposited into the fallopian tubes. Nature. 1951;168(4277):697–698 ( View )

Choza J. (1991): Antropología de la Sexualidad. Ed. Rialp. Madrid, 1.ª Edición ( View )

J Clin Invest. (2010). Fertilization: a sperm’s journey to and interaction with the oocyte. Research Institute for Microbial Diseases, Osaka University, Osaka, Japan. School of Biological and Biomedical Sciences, Durham University, United Kingdom. 120(4) 984–994 ( View )

Lennart Nilsson, A portrait of the sperm. In: The functional anatomy of the spermatozoan, ed. Bjorn A. Afzelius (New York: Pergamon, 1975), 79-82.

Martin E. The egg and the sperm: how science has constructed a romance-based on stereotypical male-female roles. “Signs”. Vol. 16. No. 3 (Spring, 1991), pp. 485-501. Published by: The University of Chicago Press ( View )

Stein KK, Primakoff P, Myles D. Sperm-egg fusion: events at the plasma membrane. J Cell Sci. 2004; 117(Pt 26):6269–6274 ( View )

Paul M. Wassarman, The biology and chemistry of fertilization, Science 235, No. 4788 (January 30, 1987): 553-60, esp. 554 ( View )

Paul M. Wassarman, Fertilization in mammals, Scientific American 259, no. 6 (December 1988): 78-84, esp. 78, 84

FAQs from users: 'How long does it take from sperm production to ejaculation?' , 'How can ovulation be calculated so that the sperm and egg meet?' , 'How long can a sperm live in the female reproductive tract?' , 'How many sperm make it to the egg?' , 'How long does it take sperm to reach the egg?' , 'After sperm meets egg, how long until implantation?' , 'How does it feel when sperm meets the egg?' , 'How long after IUI does sperm meet egg?' , 'Can sperm meet egg before ovulation?' , 'Where do the sperm cells pass through on their way to the egg?' , 'Where does the sperm go when you have a vasectomy?' , 'Where does the sperm need to get to, to be able to fertilize the egg?' , 'When pregnant, where does sperm go?' , 'When does sperm die outside the body?' , 'When does sperm leave the female body?' and 'How many sperm fertilize an egg for identical twins?' .

Authors and contributors

Find the latest news on assisted reproduction in our channels.

And when do men expel the so-called pre-ejaculatory fluid? I want to know it because then my boyfriend and I will be able to use the pull-out method more accurately. Thnxs!

Hello Katie1,

Firstly, the pull-out method, coitus interruptus , or withdrawal method is not a safe birth control method because it does not prevent you from the transmission of STDs (sexually transmitted diseases) and HIV infection (AIDs). Besides, it is actually an extremely unreliable method.

Apart from that, there are several theories about why pre-ejaculatory fluid exists, none of them proved. While some say the only function of this fluid is providing some lubrication for intercourse, others believe they protect the sperm by acting as a sort of pre-clearing of the urethra, making the environment more conductive for sperm to survive the journey and lowering the acidity. On the other hand, the function of sperm is reproduction.

I hope I have clarified your concerns,

My husband has had a vasectomy and we want to try for a baby. Is there any way we can do this without surgery?

It is possible for a man to become a father after again after a vasectomy. However, this is not possible without some kind of surgical treatment. There are different options available and you can find lots more information in our article: Pregnancy after vasectomy

I hope this helps and good luck.

Interesting article, thanks. It is very interesting that so many sperm are needed to fertilize just one egg and reading this makes me realize why!

Leave a Reply

Privacy Overview

Where do egg cells travel down from?

The egg cells travel down from the ovary to the fallopian tubes. If the egg is fertilised it then travels to the uterus where it implants and may developinto a baby. If the egg isn't fertilised then it is reabsorbed into the body in the fallopian tubes.

Add your answer:

Where do egg cells travel from?

The egg cells travel down from the ovary to the fallopian tubes. If the egg is fertilised it then travels to the uterus where it implants and may developinto a baby. If the egg isn't fertilised then it is reabsorbed into the body in the fallopian tubes.

Egg cells travel down the on their way to the?

Egg cell begin in the ovaries, and then move through the fallopian tubes to the uterus.

Where do the egg cells travel through in the womans body?

Egg cells are released from the ovaries and travel through the fallopian tubes to the uterus. If fertilization does not occur, the egg is shed along with the uterine lining during menstruation.

Where do the womans egg cells travel through?

The fallopian tubes.

What travels down the pollen tube to fertilize the pistil?

The male gametes (sperm cells) travel down the pollen tube to fertilize the female gametes (egg cells) located in the pistil. This process is essential for sexual reproduction in plants.

Do egg cells have enzymes to digest cell membranes?

Yes, egg cells have enzymes called hyaluronidases that help break down the cell membrane of the egg. This allows sperm to penetrate the egg during fertilization.

What is the pathway of an egg from the ovary to the anus?

An egg cannot travel from the ovary to the anus. An egg, however, DOES travel from the ovary, to the fallopian tube, down into the uterus. If fertilized, the egg will implant in the uterine wall. If unfertilized, the egg will be discharged during the menstrual flow.

How big do cells get?

The largest cells in length are the nerve cells that run down an animal's leg and in volume an Ostrich egg is a cell.

How the egg cell travel?

The egg begins in the ovaries. Once an egg leaves an ovum it then travels down the fallopian tubes, then to implant in your uterus for 3 weeks and wait for fertiliztion.

What do sperm cells travel down on there way out of the body?

Sperm duct and urethra.

Does the stigma of a flowere contain sperm cells?

The answer is no. The anther contains pollen which contains sperm cells. Mainly through pollination, the pollen from the anther travels down the pistil, and meets the egg where it fertilizes the egg.

Can meiosis form egg cells?

yes. it does forms egg cells

Top Categories