The Sperms’ Journey to the Egg

the sperms journey to the egg
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What is the goal of a sperm cell?

The goal of the sperms’ journey to the egg is to fertilize it. To do so, the sperm cell must pass through a long and challenging path. This is one of the reasons why the total number of motile sperm cells is very important, and a key parameter for a man’s potential to reach pregnancy with his partner.

Fig 1the sperms journey to the egg

The sperms’ journey to the egg begins with millions of sperm cells that are released into the female reproductive tract during intercourse. The sperm cells gain their full ability to swim when they are ejaculated into the reproductive tract [1],[2].

Upon ejaculation, the sperm cells are enclosed in a fluid called seminal plasma or semen, which is a mix of fluids from the testes, seminal vesicles, prostate, and the bulbourethral glands. The fluid contains elements which protect the sperm cells during their journey towards the egg. The semen thickens and helps the sperm cells stay inside the woman – as close as possible to the cervix, which is the “gate” to the egg. Liquid extends from the cervix, allowing the sperm cells from the semen to swim into the cervix. Only the strongest sperm cells will make it this far. Once through the cervix, the sperm cells swim across the uterus and into the fallopian tubes as illustrated in figure 1.

Fig 2the sperms journey to the egg

Only the strongest make it this far

Of the millions of sperm cells deposited during intercourse, only very few have the potential to reach the fallopian tubes. Once inside the tubes, the sperm cells follow signals (a process called chemotaxis) from the supportive cells (called the cumulus cells) of the egg [3]. On the way, the sperm cells undergo a series of biochemical and functional changes. These prepare the sperm cells for fertilization.

Eventually, the sperm cells meet a barrier of cumulus cells surrounding the egg. To pass through this barrier, the sperm cells must use their very special ‘stroke’, known as hyperactivation. The sperm cell then has to pass another barrier called the ‘zona pellucida’, an additional layer of the egg. To pass this barrier the sperm cells now must undergo a process called the acrosome reaction. That’s where a deposit at the top of the sperm cell releases enzymes. These enzymes will break down the zona pellucida barrier, allowing the sperm to penetrate the egg [4], [5]. See figure 2.

When the sperm cell’s head is inside the egg, the tail of the sperm detaches. At that moment, the zona pellucida becomes impermeable to other sperm cells.

When inside the egg, both the egg and the sperm prepare for a genetic fusion. After this, the 23 chromosomes from the egg and the sperm cell respectively, fuse together. They generate the 1st cell that gives rise to new life, called the zygote.

After fertilization, the zygote moves through the fallopian tube to attach itself to the inner wall of the uterus.

What about twins? Is the sperms’ journey to the egg different?

Twin pregnancies happen either when two fertilized eggs attaches to the uterus simultaneously (dizygotic twins). Or it happens when one fertilized egg splits into two embryos (monozygotic twins).

With the ExSeed Home Sperm Test, we assess how many sperm cells there are in a semen sample and how many of them are swimming. As you may see from this post, these are important parameters in determining if the sperm cells will reach the egg.

As always, don’t hesitate to contact us if you have any comments or questions!

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20 thoughts on “The Sperms’ Journey to the Egg”

  1. Name

    … thx for my homework answers….

  2. Min

    Hello! This is my first comment here so I just wanted to give a quick shout out and say I really enjoy reading your articles. Can you recommend any other blogs/websites/forums that cover the same subjects? Thanks for your time!

    1. Emil Andersen

      Thank you very much for your comment! You are always very welcome to suggest topics that you would like us to cover! Unfortunately, we do not know of other sites at the moment, but would be happy to share!
      Kind regards
      Emil, ExSeed Health Team

      1. Manuel

        Después de haber el amor con mi novia y posterior eyaculacion ,quedó todo el semen dentro ¿a Qué es debido?

  3. name 666

    thanks for my sperm assessment

  4. Christian

    Thanks for this vital information, but my worry is how to have a male child or twins. Can you be of help?

    1. Emil Andersen

      Thank you for your comment.
      Currently, there is no natural way to select for either sex of your baby or twins. Sex selection is illegal in most countries. A higher chance of twins is possible through artificial reproductive techniques.
      Kind regards
      Emil, ExSeed Health Team

  5. Lucy

    thx amazing for my sperm homework

  6. simmy javile

    ngl i just used this to copy and paste for my homework

    1. Lauren Tivy

      yoou really shouldnt be that proud of being so lazy. I hope you take some time and think about your actions

    2. Aidan

      what the. you have no academic integrity. do something on your own for once

  7. Caitlin Lydon

    Thanks it is really helpful for my homework in year 7 it is amazing

  8. Silvia

    Mi duda es la siguiente. Tengo entendido que el óvulo es rodeado por muchos espermatozoides a la vez para poder fecundarlo, todos tienen los mismos mecanismos que degradan la pared del óvulo, sin embargo solo uno logra la fecundación. ¿Cuál es ese fenómeno que explicaría dejar entrar a un espermatozoide concreto, si todos son iguales estructuralmente? Es decir, ¿qué tiene el espermatozoide ganador, que consigue entrar y fecundar, que no tengan los demás?
    Muchas gracias y saludos.

  9. Silvia

    Well, my question is this.
    I understand that the egg is surrounded by many sperm at the same time in order to fertilize it, all of them have the same mechanisms that degrade the wall of the egg, however only one achieves fertilization. What is that phenomenon that would explain letting a particular spermatozoon in, if they are all structurally the same? In other words, what does the winning spermatozoon have that manages to enter and fertilize that others do not? Thank you very much and regards.

    1. Sadia

      All the sperm actually have the same features, it’s just that after one sperm manages to enter, the egg shoots out a substance, which hardens the egg, not allowing any other sperm to enter.
      Hope this helped.

  10. Sandra

    Si introduzco a penas mi novio eyacula fuera de mi el semen y estoy en mis dias fertiles puedo quedar embarazada

  11. Hunter Inman

    Whats up! I just would like to give an enormous thumbs up for the nice information you have here on this post. I can be coming again to your blog for extra soon.

  12. Me love

    I think is first come, first serve. All the other sperms are capable but the first sperm to reach the egg takes control and immediately fertilises the egg.

  13. board

    GooԀ dɑy! Do you ᥙse Twitter? I’d like to follow you if that would be okay.
    I’m absolutely enjoyіng yоur blog and look forward to new posts.

  14. Santiago

    Way cool! Some extremely valid points! I appreciate you writing this and also the rest of the website is extremely good.

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