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The Journey of “Jizz”

Updated: Mar 17, 2023


Everyone talks about sex but less is known about the biology of male ejaculate and what contributes to levels of fertility. Semen is colloquially known as “jizz” or “sperm” or "load", undertakes a remarkable journey to fertilize an egg, and hence this blog covers the journey (and trials and tribulations) of jizz.


In this blog, we will explain the science behind the journey of sperm and discuss, what makes high-quality sperm? What hinders fertility and why is male infertility rising worldwide?



The Spunky Contents


Male ejaculate, also known as semen, contains a combination of fluids from the male reproductive system. The composition of semen can vary slightly from person to person, but it generally contains:


  1. Sperm: Sperm are the reproductive cells that are necessary for fertilization and the creation of a new individual.

  2. Seminal fluid: This fluid is produced by the seminal vesicles and contains fructose (a sugar that provides energy for the sperm), amino acids, and enzymes that help the sperm to function properly.

  3. Prostatic fluid: This fluid is produced by the prostate gland and contains enzymes, proteins, and minerals that help to nourish and protect the sperm.

  4. Bulbourethral fluid: This fluid is produced by the bulbourethral gland and helps to lubricate and neutralize acidic urine in the urethra before ejaculation.


The exact volume and composition of ejaculate can vary depending on a variety of factors, including age, diet, hydration levels, and sexual activity.






Sperm – How do these little wrigglers come about?

Sperm are made in the testes or balls through a process called spermatogenesis. This process involves cell divisions that create spermatids. These spermatids then become mature spermatozoa through a process called spermiogenesis. During this process, the sperm develop a tail, which helps them swim. Once mature, the sperm are stored in the epididymis. During ejaculation, the sperm are mixed with fluid to create semen, which is then ejaculated out of the penis during sexual activity or masturbation.

How does a sperm fulfill its purpose?

Sperm meets the egg during a process called fertilization, which typically occurs in the fallopian tubes of the female reproductive system. When a man ejaculates during sexual intercourse, millions of sperm are released into the vagina. From there, the sperm swim through the cervical mucus and into the uterus. Once in the uterus, the sperm must then navigate their way into one of the two fallopian tubes.

If a woman has recently ovulated (released an egg), the sperm may encounter the egg in the fallopian tube. The sperm use their tails to swim toward the egg and once a sperm successfully penetrates the egg, fertilization occurs. This fertilized egg, now called a zygote, will then travel down the fallopian tube towards the uterus where it will implant in the uterine lining and begin to grow into a fetus. The purpose of 99.99% of all sperm is to pave the way to that one successful sperm that ends up making the baby. If you ever feel down, know that you were once the winner of the most competitive, difficult, and important race in human existence. The race to the egg.

During in vitro-fertilization (IVF) this process is a bit different. The sperm's journey is shortened significantly, whereby the ejaculation is into a plastic cup and not a vagina. For the woman, it involves stimulating the ovaries and retrieving eggs. The eggs are then fertilized with the sperm in a laboratory, after which they are grown in culture to create embryos, and those embryos are then transferred into the uterus. A pregnancy test is then conducted to determine if the procedure was successful.





How does one make a high-quality sperm load and why is there a global reduction in sperm quality?


A recent report found that there is a global reduction in the quality of sperm, in fact, one study by epidemiologist Hagai Levine (2022) suggests that globally there could have been as much as a 50% decrease in sperm quality since the year 1970.


A high-quality semen is one that contains a healthy and optimal amount of sperm with good motility (movement) and morphology (shape) and is free from any infections or abnormalities. The quality of semen can be influenced by various factors, including:


  1. Age: The quality of semen tends to decrease with age, with older men producing fewer and less motile sperm.

  2. Lifestyle: Factors such as diet, exercise, and smoking can impact the quality of semen. A healthy diet and regular exercise can promote better semen quality, while smoking and excessive alcohol consumption can harm sperm health.

  3. Medical conditions: Certain medical conditions such as a varicocele, infections, hormonal imbalances, and genetic disorders can affect the quality of semen.

  4. Environmental factors: Although studies have mixed findings in terms of various toxins and sperm quality, it is always a good idea to limit exposure to pollution, pesticides, and heavy metal toxins, especially when trying for a baby.

  5. Temperature: tight boxers, cycling shorts, saunas, and having a laptop on your lap or heated blankets can all increase the temperature of your testes, which reduces sperm count.


In men, making sperm requires enough testosterone and the right temperature in the testes. An important study bringing together a range of research by epidemiologists Hagai Levine and Shanna Swan showed that the lowering of sperm count is a global problem.


Hagai and Swan’s study found that as sperm counts decreased, testosterone levels also decreased. We're not sure what causes the decline, but it might be because of things like being overweight, eating unhealthy food, stress, and being around harmful chemicals. Although the jury is still out on why globally there is a reduction in sperm quality it is widely suggested that it is the cumulative effects of all the factors mentioned above that are magnifying each other's negative effects.


Conditions during pregnancy may also influence sperm count. A baby in the womb can be affected by the same things that affect his mother, like unhealthy food, smoking, and being overweight. This can change the way his genes work and be passed down to his kids, this is called epigenetics. For example, a study by Istvan (2021) (Link to paper) found a link between pregnant women being exposed to certain types of chemicals at work and their sons having poor sperm quality when they grew up. They looked at chemicals that could be harmful to the endocrine system and found that when moms were exposed to pesticides, phthalates, and heavy metals, their sons had lower semen volume and sperm count.



Takeaway


If you have had trouble conceiving as a couple, it may be worth going to get your sperm checked out by a medical professional. There are many ways that doctors could help, such as IVF, surgery to remove varicocele or give you lifestyle tips to increase your sperm count naturally. It’s important to understand that having low sperm count or motility is a common issue and nothing to be ashamed of, and there are many ways to boost sperm count.


Refs

  1. Deng, Z., Chen, F., Zhang, M., Lan, L., Qiao, Z., Cui, Y., An, J., Wang, N., Fan, Z., Zhao, X. and Li, X., 2016. Association between air pollution and sperm quality: a systematic review and meta-analysis. Environmental pollution, 208, pp.663-669

  2. Hagai Levine, Niels Jørgensen, Anderson Martino-Andrade, Jaime Mendiola, Dan Weksler-Derri, Maya Jolles, Rachel Pinotti, Shanna H Swan, Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries, Human Reproduction Update, Volume 29, Issue 2, March-April 2023, Pages 157–176, https://doi.org/10.1093/humupd/dmac035.

  3. M Istvan, R Rahban, B Dananche, A Senn, E Stettler, L Multigner, S Nef, R Garlantézec, Maternal occupational exposure to endocrine-disrupting chemicals during pregnancy and semen parameters in adulthood: results of a nationwide cross-sectional study among Swiss conscripts, Human Reproduction, Volume 36, Issue 7, July 2021, Pages 1948–1958, https://doi.org/10.1093/humrep/deab034

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