To really understand how your everyday life can affect your sperm, you should understand how healthy sperm is made in the first place.
Sperm production in numbers
A healthy man produces approximately 100 million viable sperm cells each day, although only a tiny few of those will ever go on to try fertilizing an egg.
Unlike a woman who will have around 400 mature eggs throughout a lifetime, which can be released from the follicles in the ovaries and potentially be fertilized, a healthy man will produce billions of sperm in his entire lifetime. All the sperm production and maturation take place in the lumen of the seminiferous tubules of the testis as shown in figure 1.
Fig 1: The testes are composed of numerous thin, tightly coiled tubules known as the seminiferous tubules. Within the walls of these tubules the sperm cells are produced and matures. Also, in the tubes, there are many different cells of which the most important is the Sertoli cells. These cells function to support and nourish the immature sperm cells by giving them nutrients and blood products.
Once the sperm cells are mature, they are transported to the Epididymis and later into Ductus deferens for temporary storage and where they here undergo another maturation process necessary for them to acquire the ability to be motile (swim).
The production of sperm cells (Spermatogenesis)
The production of sperm is called spermatogenesis and is a tightly regulated (Fig 3: Sperm cell anatomy) and complex process. The sperm production time varies from individual to individual, but the average process from beginning to ejaculation takes about 64 days (With a range of 42-76 days) . The process is initiated by sex the hormones (FSH, LH, and Testosterone) and happens in several steps where an immature sperm cell slowly develops and divides, resulting in a fully mature sperm cell that can swim and fertilize an egg. The process is controlled by the sex hormones coming from the hypothalamus; a gland located in the brain. Figure 2 shows a process called spermiogenesis which is the final stage of the spermatogenesis, where the maturation of the spermatids into mature motile spermatozoa happens.
Fig 2: The figure shows the spermiogenesis – the process where a sperm cell undergoes different steps (1-7) to mature in the seminiferous tubules of the testes. In step 1 the cell is immature and called a spermatid differentiates into a spermatozoon which is shown in step 7.
The production of sperm cells is highly dependent on optimal conditions for the process to occur correctly and is essential for sexual reproduction. When a man is sexually stimulated, the mature sperm mixes with seminal fluid; a whitish liquid produced by the seminal vesicles, the bulbourethral glands, and the prostate gland. Sperm cells and seminal fluid together is called semen.
As you see in figure 1, the testicle is divided into sections where many tubes (seminiferous tubules) run. It is in these tubes the sperm production occurs. When they have been produced, the sperm cells are then transferred into the epididymis where they mature to become active swimmers.
What can affect healthy sperm?
A mature and healthy sperm cell looks like the one shown in figure 3.
Fig 3: Sperm cell anatomy
As you can see, the sperm cell can be divided into 3 parts:
- Head: contains DNA and enzymes that can penetrate an egg during fertilization
- Midpiece: is the cell motor that produces energy for swimming with the help of the tale
- Tale: makes lashing movements whereby the sperm cell can swim and move forward.
Several factors can potentially disturb both sperm production in the testes and the maturation in the epididymis. In the testicles, disorders like deformed testicles or misplaced testicles can affect sperm production. Even in normal looking testes, genetic factors may affect how sperm cells are produced and function.
Factors like overheating, oxidative stress, varicocele, hormonal changes, radiation, and testicular cancer may disturb both production and maturation, in part by inducing DNA damage and cell structure damage, which both may lead to sperm cell death .
To produce healthy sperm that have the power to swim fast and penetrate a female egg, you must make sure that your sperm production is under optimal conditions!