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Sperm cells are “made” in the testicles — most people know that — but far fewer people actually know how sperm are produced and what this process involves. Let’s explain it briefly:
How sperm are formed
The process of sperm formation is called spermatogenesis. It takes place in the testicles, where the seminiferous tubules are located — long, coiled tubes that occupy almost the entire volume of the testicle.
The main function of these tubules is to produce sperm. The process begins with spermatogonia, the germ cells that line the tubule walls. These divide by mitosis into two types of cells: type A and type B spermatogonia. Type A cells continue to replicate, generating more type A and type B spermatogonia, while type B spermatogonia give rise to primary spermatocytes which, as they mature, eventually become sperm cells. Sertoli cells play a key role, providing structural support, nutrition, hormonal regulation and helping to eliminate abnormal germ cells during spermatogenesis. Within the testicle we also find Leydig cells, which produce testosterone.
How long do the testicles take to produce sperm?
A sperm cell takes around 65–70 days to reach a sufficient degree of maturity to fertilise an egg. In other words, it takes about two and a half months for a sperm cell to fully mature. Once sperm are produced in the seminiferous tubules, they are released into the tubule lumen and transported to the epididymis, where they complete their maturation. The epididymis is a narrow, elongated tube located at the upper and back part of the testicle. The sperm that are ejaculated are stored in the epididymis, not inside the testicle itself.
For this production and maturation process to work properly, the testicle must be at a temperature roughly one degree lower than the rest of the body. This is why, in winter when it is cold, the testicles are held closer to the body, and in summer, when it is warm, they hang further away.
How long does a sperm live?
The lifespan of a sperm cell varies depending on the conditions it is exposed to. In optimal conditions within the female reproductive tract, sperm can survive for up to five days. In most cases, however, sperm live between 48 and 72 hours outside the body. After this time, sperm viability and motility decline.
We must remember that a man’s health, lifestyle and other external factors are key determinants of sperm quality and longevity.
How can we improve sperm quality and production?
Although every man and every ejaculate are different, experts offer some recommendations that may help improve sperm quality and production.
1. Maintain a healthy lifestyle.
Eating a balanced diet, exercising regularly at a moderate level and avoiding alcohol and tobacco can all have a positive impact on semen quality.
2. Avoid tight underwear.
It is important to maintain an appropriate temperature, as the testicles need to be slightly cooler than the rest of the body to produce sperm. For this reason, it is advisable to avoid very tight underwear, which can raise testicular temperature.
3. Avoid recreational drugs.
Recreational drug use is harmful to all aspects of our health and, as you might expect, it also negatively affects fertility.
Remember that every person and every situation is unique. Different factors can affect each individual in different ways. If you have any doubts or concerns about your semen quality, it is advisable to consult a fertility specialist for a personalised assessment and work-up.
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