Journey of a Sperm Cell: How Your Swimmers Gather For the Race of their Lives
Sperm is the male reproductive cell, making it a vital part of the equation of life. As you might already know, they are stored in the testicles. However, what you might not know is what exactly happens within the confines of your testicles.
Read on to find out how your swimmers take shape right from an early age up to when they’re ready to shoot out and embark on the race of their lives.
How are sperms made?
Sperms go through a relatively lengthy process to acquire their characteristic appearance of a head and tail. This process is known as spermatogenesis – the generation of sperms.
This process starts deep within the testicles in an area known as the seminiferous tubules. Here, the stem cells that line the tubules differentiate into spermatocytes, which transform into haploid spermatids.
These spermatids divide further to form spermatozoa – the actual sperm cells. These, however, are still immature and need to get ready for the long journey out of your penis, into the vagina and all the way to the fallopian tubes.
To get ready for this task, the juvenile sperm cells go to the epididymis – the long coiled tube that hugs the side of each of your testicles.
How many sperms do you make and how long does it take?
In a single day, your testes produce about 300 million sperms. Though this seems excessive, only a third of this will mature to become viable swimmers that are capable of fertilizing a woman’s egg.
The entire cycle from the stem cells in the seminiferous tubules to the mature sperms in the epididymis lasts close to three months. In that period you make about 8 billion sperm cells. That is more than the population of the entire planet – all in your testicles!
However, given that every time you ejaculate you release anywhere from 20 to 300 million sperms per milliliter, this number seems justified.
What happens when you climax during sexual intercourse?
The sperms mature and perfect their motility in the epididymis. Its stature gives them ample room to figure out how to use their tails to move. Once they are mature enough, they are stored in the vas deferens – a duct that transports them from the testes in readiness for ejaculation.
When you climax during sex, this duct contracts and ushers the sperms towards the base of your penis. At this point, the prostate and the seminal vesicles secrete fluids that form semen. The contraction of the muscles at this base causes you to ejaculate, spurting out the entire concoction of seminal fluids and sperms.
If you’re still young and virile, the average speed of this ejaculate at the moment of exit is around 28 miles per hour.
How do the sperms reach the egg?
Once the semen lands in the vaginal canal near the cervix, only a small percentage will make it through into the uterus. The rest either fall victim to the acidic environment of the vagina or flow back out of the female body.
If you ejaculated 200 million sperms, you’ll find that only 2 million will try to make it through to the uterus. Half of that will get tangled up in the mucus plug.
Those that make it through now have to swim a relatively long distance towards the egg in the fallopian tube. The majority will be left by the wayside as energy levels run out or when they get stuck in the mucus lining along the uterus.
The great trek
The distance from the cervix to the egg in the fallopian tube is about 15 centimeters. To you and me, this seems a very short distance. However, you have to take into account the microscopic nature of the sperms. To them, this is the greatest trek they have ever attempted since navigating the coils of your epididymis.
Generally, the sperms have an average swimming speed of 8 inches per hour. Depending on their structure and energy reserves, some sperm can reach the fallopian tube in a half hour whereas others can take up to 12 hours.
At the end of it all, however, only one sperm can fuse with the egg, the rest being denied by the zona pellucida. The sperms that don’t get the prize can live in the female body for up to 7 days, surviving on the nutrients present therein. On the other hand, the egg is only available for fertilization by the sperms for only 24 hours. After that, it disintegrates.
All in all, the journey of the sperm is a long one, beginning from your testicles. From the nourishment it receives there to the various hurdles in the female body along the way to the egg, the sperm needs a lot of hardiness and a bit of luck to reach its goal. If everything goes its way, that very sperm can end up creating your next offspring.