Male Fertility – Parts & Functions of the Male Reproductive System

By (senior embryologist), (embryologist) and (fertility counselor).
Last Update: 09/20/2018

Male fertility is defined as the ability of men to cause pregnancy in women and subsequently have a baby. In this sense, and for a man to be able to conceive, it is necessary for his reproductive system to work properly.

In short, for a male to be considered fertile, the following processes are necessary:

  • The testes have to produce enough sperm in terms of quantity and quality in order to be able to fertilize the female's egg cell.
  • Sperm ejaculation has to occur inside the vagina of the woman. This can only be achieved by having full sexual intercourse.

This system is connected and regulated by the sex hormones of males, which start working during puberty.

Structure of the male reproductive system

The male reproductive system consists of a set of internal and external organs depending on their location. What follows is a detailed classification of both parts:

External organs

The most important external genitalia of men are the penis and the testes or testicles, which are considered to be external sexual organs because they can be found outside the abdominal cavity.

Testes or testicles
These egg-shaped (hence the common name balls) organs are located inside a sack of skin called scrotum. Their main function is the production of sperm (spermatogenesis) inside the seminiferous tubules, as well as the production of testosterone.
It is the primary male sex organ used during copulation. Its main function is to place the semen inside the vagina of the female during intercourse. The penis is made of the corpus cavernosum, which is filled with blood to cause an erection, and the corpus spongiosum, which ends at the glans penis.

The testes are located externally because they have to be kept at a lower temperature than that of the body to promote sperm production. Alterations in the anatomy of the male reproductive system can lead to male infertility, as in the case of cryptorchidism.

Internal organs

The genitalia of the internal male reproductive organs can be found mainly within the pelvis. Their function is to release and transport the compounds that give raise to spermatozoa.

This tube is made of the whole set of seminiferous tubules, and is located behind each testis. It stores spermatozoa and creates the adequate atmosphere for their development.
Vasa deferentia or ductus deferens
It is a tube that transports sperm from the epididymis to the ejaculatory ducts.
Seminal vesicles
These glands are responsible for producing almost all the substances contained in the ejaculate. Moreover, they nourish and provide energy to the sperm that travel with it.
It is a gland that segregates seminal fluid to protect the sperms. The bulbourethral glands or Cowper's glands, which are responsible for releasing a lubricant fluid, are located under the prostate.
Males use this conduct for both ejaculation and urination. It opens at the end of the penis.

Contrary to what happens in females, the urethra of males is part of both the excretory and the reproductive systems, as it is used for ejaculating and urinating interchangeably.

When do males start producing sperm?

Since they are born, boys have a different reproductive system from that of girls. Their reproductive organs, however, are not functional until they reach puberty.

When males turn 11-12 years of age, their endocrine system starts releasing male sex hormones (androgens), thereby beginning a period known as sexual maturity. It is at this point, which is called puberty, when they start producing sperm in the testes and developing the common male sexual characteristics:

  • Increase in height and muscle mass
  • Hair becomes larger and thicker
  • Appearance of facial hair
  • Deepening of the voice
  • Increase in body fat
  • Shoulders and chest become broader
  • First conscious ejaculations occur

It is from this moment on when a boy becomes fertile: he is now a teenager, which means that he has now the ability to cause pregnancy in women, that is, to have offspring.

During adulthood, it is actually very difficult to check if a man is fertile or not naturally. However, common signs of fertility in males include, but are not limited to, being free from stress, exercising regularly, not smoking, drinking alcohol or having toxic habits, using boxers instead of briefs, and being sexually active, among others.

Male fertility by age

In spite of the common belief that men can have children at any age, the truth is that a man's age does matter. Although not as sharply as in females, the chances for a man to conceive decrease as he gets older.

Sperm quality starts decreasing after 40, and especially from age 50 onwards, which means that it might take longer for a man's partner to get pregnant and, if it occurs, there exists an increased risk of miscarriage.

The following graph shows how a man's age affects not only the chances of causing pregnancy in women, but also the likelihood of miscarriage, which at the same time decreases the live birth rates:

In short, between the ages of 30 and 50, the average man's sperm quality declines by up to 30% in volume. Also, sperm motility is about 37% poorer, and morphology is five times more likely to be altered. This equals a greater potential for genetic abnormalities.

For couples undergoing IVF, the risk of failure is more than five times higher if the age of the male partner is equal to or greater than 41. In fact, statistics show that children with older fathers are more likely to have an autism spectrum disorder than those fathered by men aged 30 or younger.

Pathway of sperm

An essential aspect of male fertility is spermatogenesis, a process that takes place within the seminiferous tubules, that is, the structures that can be found within the testes.

Sperm production is a complicated process. It involves the successive division of spermatogonia, which are undifferentiated male germ cells. The entire process of spermatogenesis is estimated to take between 64 to 72 days.

Once produced, sperm are stored in the epididymis, where they acquire the appropriate motility. Then, they travel to the vasa deferentia, where they mix with the seminal fluid released by the accessory glands (seminal vesicles, prostate, and bulbourethral glands). Finally, the sperm produced reach the urethra and come out of the man's body with ejaculation.

After intercourse, as long as ejaculation occurs, semen enters the vagina, and that is the moment when they start their journey toward the female reproductive tract thanks to their ability to swim and move forward. Only those able to meet the egg in the Fallopian tube have the chance to fertilize it and give raise to an embryo.

Any alteration in the male reproductive organs that prevent them from producing or transporting sperm, as well as hormonal imbalances, may lead to male sterility.

If you need to undergo IVF to become a mother, we recommend that you generate your Fertility Report now. In 3 simple steps, it will show you a list of clinics that fit your preferences and meet our strict quality criteria. Moreover, you will receive a report via email with useful tips to visit a fertility clinic for the first time.

FAQs from users

How long does it take for sperm to be ejaculated since their production?

By Emilio Gómez Sánchez B.Sc., Ph.D. (senior embryologist).

Spermatogenesis is the process whereby male reproductive cells are formed, from the immature ones, spermatogonia, until the mature ones, spermatozoa. This complicated process occurs within the seminiferous tubule in the testis and takes about 64-72 days.

Once spermatozoa (sperm cells) have been produced, they leave the testis and travel to the epididymis, where they will acquire the necessary motility in a process that lasts 10 days approximately. Spermatozoa will be stored in the epididymis until they are expelled with ejaculation. When ejaculation starts, sperm travel through the vasa deferentia and mingle with the seminal fluid that originates in the secretory glands, creating what we all know as semen. Finally, it is expelled through the urethra.

What affects fertility in males?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Cigarette smoking, alcohol drinking, street drug use, pollution, radiation, chemicals, drugs, heavy metal exposure, etc. can lead to low sperm count or poor sperm motility. Also, hot baths, tight-fitting underwear, sitting for long periods of time, working with computer laptops on the lap, and carrying cellphones in the front pocket are habits that damage the overall quality of sperm.

What increases fertility in males?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Foods, vitamins, supplements, and other natural remedies said to improve fertility in males can work, yet not in the most severe cases. For instance, improving your diet, reducing chemical exposure, exercising regularly, and taking nutritional supplements and vitamins can help to some extent.

How can chemotherapy affect fertility in males?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Since chemotherapy works by killing cells that are dividing quickly, and sperm cells are included within this group, chemo affects them to a large extent. Permanent infertility can occur if all the spermatogonial sperm cells are affected to the point that they can no longer produce sperm. This risk is dependent on the patient's age, the type of drug used, and the dose given.

What is the male reproductive organ that makes testosterone?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

The testes or testicles are the organs responsible for making testosterone, which is the primary male sex hormone.

Does diabetes affect fertility in males?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Diabetes can cause male infertility in three ways:

  1. It affects the health of small blood vessels and lowers testosterone levels, which causes erectile dysfunction.
  2. Given that it lowers testosterone levels, it reduces the man's libido.
  3. The combination of these three factors contributes to reducing the ejaculate volume.

Suggested for you

If you are interested in learning more about the sperm's journey to the egg, we recommend you to read the following post, which includes pictures that will help you understand the process from beginning to end: How sperm meets egg with pictures.

On the other side of the coin, there exist different types of male infertility depending on what is causing it. We have created a comprehensive guide to male infertility so that you are able to understand it and consider your chances of starting a family in spite of sterility. Here you go: What causes male infertility?

We make a great effort to provide you with the highest quality information.

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Authors and contributors

 Emilio Gómez Sánchez
Emilio Gómez Sánchez
B.Sc., Ph.D.
Senior Embryologist
Bachelor's Degree in Biology from the University of Seville. PhD in Biology from the University of Valencia. Large experience as an Embryologist Specialized in Assisted Reproduction. Currently, he is the IVF Lab Director of Tahe Fertilidad. More information about Emilio Gómez Sánchez
License: 14075-MU
 Zaira Salvador
Zaira Salvador
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Technical University of Valencia (UPV). Biotechnology Degree from the National University of Ireland en Galway (NUIG) and embryologist specializing in Assisted Reproduction, with a Master's Degree in Biotechnology of Human Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI) More information about Zaira Salvador
License: 3185-CV
Adapted into english by:
 Sandra Fernández
Sandra Fernández
B.A., M.A.
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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