By: Maryam Rahbar MSc DPhil (Pending, Oxon), the Chief Scientific Officer of Jack Fertility.
Where does sperm come from?
Sperm production is constantly occurring in the testicles with an average of millions of sperm being produced daily. The process takes approximately 60 days in the testicles after which the sperm move through the epididymis and mature which takes approximately 14 days. The process can be slightly longer or shorter depending on the physiology of the individual and other factors such as genetics and medical conditions. In this blog post, we’ll take a more scientific approach in understanding the steps involved in sperm production.
How is sperm production initiated?
It all starts in the brain and the hormones that are released. In more scientific terms, the hypothalamus section of the brain releases gonadotropin-releasing hormone (GnRH) which acts on the anterior pituitary to release two hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH travel through blood to the testicles where they initiate sperm production (spermatogenesis) .
Let’s delve a bit more into the production of sperm in the testicles
In response to LH and FSH, leydig cells and sertoli cells in the testicles are activated. Leydig cells produce testosterone which maintains spermatogenesis while sertoli cells nourish and provide regulatory signals to support the developing sperm cell.
Within the testicles, there are semineferous tubules (coiled tubes) where spermatogenesis occurs. On the periphery of the tubes, primary spermatocytes are present which divide to form the secondary spermatocytes. These divide further to form spermatids that become spermatozoa which are the sperm cells that we are all familiar with. One primary spermatocyte divides and gives rise to four spermatids. At this stage the sperm cell contains the head, midpiece and tail but is not functional in that it lacks the ability to move and requires maturation .
The maturation process of the sperm occurs in the epididymis where the sperm gains motility and is able to travel towards the egg after ejaculation. The epididymis stores and carries the sperm until they are fully functional. Once the maturation has completed the sperm remain in the epididymis until ejaculation. During ejaculation, the sperm leave through the vas deferens where secretions from other accessory organs are added to form semen .
The effects of ejaculation on sperm levels
Once sperm is ejaculated, it only survives for a few hours outside the body. Inside the female reproductive tract however, sperm can stay alive and functional for 3-5 days due to the mucosal environment which provides the right nutrients and temperature for sperm to survive.
If ejaculation does not occur, the sperm cells are broken down and are reabsorbed. The process of sperm breakdown produces reactive oxygen species which are harmful to other sperm cells. This is the reason why it is recommended for individuals trying to conceive to ejaculate regularly every 2 to 5 days. If ejaculation occurs more frequently than this, the volume and concentration of the ejaculate will be lowered. Frequent ejaculation (daily or more than once per day) will cause a decline in sperm count .
However, other sperm parameters such as motility may increase with daily ejaculation . Although it is recommended for individuals with reduced fertility to avoid ejaculation on a daily basis as this may lower the chances of conception by lowering sperm count , newer data suggests that daily ejaculation may not have negative impacts on fertilisation .
If ejaculation does not occur on a regular basis, although the sperm count may increase, the quality of the sample will reduce due to the presence of reactive oxygen species.
It is therefore important to maintain regular ejaculation of at least every 2 to 5 days in trying to conceive.
What can go wrong?
Although spermatogenesis is a continuous process, things can go wrong at any point during the process. If not in the optimal conditions, the release of hormones, the response of the cells within the testicles, the timing of ejaculation and other factors can all have a negative impact on the sperm that is produced. There are lifestyle factors as well as genetics and medical conditions which can impact spermatogenesis and should be investigated if sperm parameters are abnormal.
Since spermatogenesis takes approximately 3 months, the effect of lifestyle changes can be seen after this time frame. It is therefore crucial to plan and make the necessary adjustments in lifestyle at least a few months in advance prior to trying to conceive. Being able to regularly check sperm parameters (through semen analysis) can allow for better understanding and planning for conception. At Jack Fertility, we provide an easy at home test which will provide a comprehensive analysis of sperm parameters allowing individuals with sperm to track their sperm production and the effects of any changes in lifestyle or medical conditions.
Even though sperm production and maturation can take months, there is a continuous supply of sperm suggesting that conception is possible at any time during a woman’s fertile window if all sperm parameters are optimal. To ensure sperm health is maintained, a healthy lifestyle can improve sperm quality and regular semen analysis can provide an insight into the process of sperm production.
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