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What are sperm?

What are sperm?

23 February 2022

What are sperm and is that what male fertility is all about?

In general terms, the so called “male-factor” fertility, is almost exclusively about the sperm. For a high level of fertility, the sperm size, speed and quality matters. This article will have a deep look at sperm, while the other known factors that can contribute to infertility are or will be available in our other articles: 

  • A blockage or absence in the transport system that deliver sperm from the testicles to the storage area or out of the body during ejaculation 
  • An imbalance or absence of the hormones involved in sperm production 
  • A failure in testicles to produce sperm, either due medical conditions such as a varicocele, after surgery procedures or cancer treatment 

So, back to sperm. 

The start of a baby-making journey can be seen as simple. All we need is an egg cell and a sperm cell. When they join ‘fertilisation’ occurs and an embryo is created. An embryo is the starting point of life that turns into a walking and talking person.  

OK, fertilising an egg is hardly the goal every time we ejaculate or have sex, but biologically this is the sole purpose of sperm. To increase the odds of a successful fertilisation, a single batch of semen contains millions of cells. It may seem a bit excessive, but the sperm have a very long way to go. A distance of 5-7cm is a long way when the length of a sperm is measured in increments of thousands of a millimetre. And a lot can go wrong along the way. On the journey to the fallopian tubes in unassisted conception, millions of sperm will die or take a wrong turn. Only a few thousand can reach this far.  

In the end, only ONE sperm will make its way through the outer shell of the egg, releasing elements that make it impossible for any other sperm to join.  

Given the hardships sperm must deal with and how many of them never make it all the way, it is understandable that the number of sperm and their quality play a significant role for a pregnancy to take place. 
 

So how are sperm produced? 

Egg cells and sperm cells are produced in completely different ways. People who have egg cells are born with them and do not produce more during their lifetime, while sperm is produced throughout life. As many as 100 million sperm every day! 

Sperm production is a complex and sensitive process that relies on many different links in a chain to function. Sperm are produced and mature in the testicles, dependent on the hormones FSH, LH and testosterone whose output is controlled by hormone glands in the brain called the hypothalamus and pituitary gland 

Sperm are formed by specialised cells found in the testicles. The sertoli cells assist the process of turning stem cells into sperm and creating new stems cells in the process.  

The sperm building blocks divide, one cell is retained for use in the future and the other goes on to produce a new batch of sperm. Renewing the reservoir of building blocks, the stem cells, means sperm production can continue as long as the levels of the needed hormones are provided by the body. The fascinating thing about stem cells is that they are constantly produced alongside sperm production, therefore lifestyle changes can make a real difference to sperm-based fertility.  

Once produced the immature sperm are transported from the testicles to a storage area called the epididymis. During this journey they mature into viable sperm. How long it takes for a sperm to be formed and fully developed varies slightly from person to person, but it is estimated that the process takes around 90 days. 
  

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