Do You Really Know About the Male Reproductive System?

Medically Reviewed by Jabeen Begum, MD on January 19, 2024
13 min read

The male reproductive system refers to the organs involved in sexual function and in the production of children in men or people assigned male at birth (AMAB). These organs are both external and internal. Together, they make, store, and ejaculate sperm, which fertilizes eggs produced by the female reproductive system in order to begin a pregnancy. The male reproductive system also produces hormones such as testosterone, which play a key role in male development.

However, those organs do not function fully until puberty. This is a period in which a child begins the physical transformation into adulthood. 

Puberty kicks off when your hypothalamus and your pituitary gland start to produce hormones that tell your testicles to start making testosterone and sperm. Testosterone, the main male sex hormone, is responsible for the growth and development of your penis, testicles, and scrotum, as well as your prostate gland and your seminal vesicles, both of which help make semen.

Testosterone also helps with what are called secondary sex characteristics. These include the following:

  • Hair on your genitals, face, and armpits
  • Muscle development
  • Deepening of your voice and other vocal changes
  • Growth spurts that increase your height


The male reproductive system performs the following functions:

  • Produces, maintains, and transports sperm (the male reproductive cells) and protective fluid (semen)
  • Discharges sperm during sex
  • Produces and secretes male sex hormones responsible for maintaining the male reproductive system


External male reproductive organs

Unlike the female reproductive system, most of the male reproductive system is located outside of the body. These external structures include the penis, scrotum, testicles, and epididymis.

  • Penis . This is the male organ used in sexual intercourse. Your penis has three parts: the root, which attaches to the wall of the abdomen; the body, or shaft; and the glans, which is the cone-shaped part at the end of your penis. The glans, also called the head of the penis, is covered with a loose layer of skin called foreskin. This skin is sometimes removed in a procedure called circumcision. The opening of the urethra, the tube that transports semen and pee, is at the tip of the penis. The glans of the penis also contains a number of sensitive nerve endings.

    The body of your penis is cylindrical in shape and consists of three circular shaped chambers. These chambers are made up of special, spongelike tissue. This tissue contains thousands of large spaces that fill with blood when you are sexually aroused. As the penis fills with blood, it becomes rigid and erect, which allows for penetration during sexual intercourse. The skin of the penis is loose and elastic to allow for changes in penis size during an erection.

    Semen, which contains sperm (reproductive cells), is expelled (ejaculated) through the end of your penis when you reach sexual climax (orgasm). When your penis is erect, the flow of pee is blocked from the urethra, allowing only semen to be ejaculated at orgasm.

  • Scrotum. This is the loose pouch-like sac of skin that hangs behind and below your penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum acts as a "climate control system" for your testes. For normal sperm development, the testes must be at a temperature slightly cooler than body temperature. Special muscles in the wall of your scrotum allow it to contract and relax, moving the testicles closer to your body for warmth or farther away from the body to cool their temperature.
  • Testicles (testes). These are oval organs about the size of large olives that lie in your scrotum, secured at either end by a structure called the spermatic cord. Most men or people AMAB have two testes. The testes are responsible for making testosterone, the primary male sex hormone. They also make inhibin B (which plays a role in sperm production), insulin-like factor 3 (which helps with the development of the testes), Mullerian inhibiting substance hormone, or anti-Mullerian hormone (which helps with the growth of male sexual organs), and estradiol (which aids in sperm production).

    Your testes also produce sperm. Within your testes are coiled masses of tubes called seminiferous tubules. These tubes are responsible for producing sperm cells.

  • Epididymis. The epididymis is a long, coiled tube that rests on the backside of each testicle. It transports and stores sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization. During sexual arousal, contractions force the sperm into the vas deferens.

Internal male reproductive organs

The internal organs of the male reproductive system, also called accessory organs, include the following:

  • Vas deferens. The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind your bladder. The vas deferens transports mature sperm to the urethra, the tube that carries pee or sperm to outside of your body, in preparation for ejaculation.
  • Ejaculatory ducts. These are formed by the fusion of the vas deferens and the seminal vesicles (see below). The ejaculatory ducts empty into the urethra.
  • Urethra. The urethra is the tube that carries pee from the bladder to outside of your body. It has the additional function of ejaculating semen at orgasm. When your penis is erect during sex, the flow of pee is blocked from the urethra, allowing only semen to be ejaculated at orgasm.
  • Seminal vesicles. The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of your bladder. The seminal vesicles produce a sugar-rich fluid (fructose) that provides sperm with a source of energy to help them move. The fluid of the seminal vesicles makes up most of the volume of a man's ejaculatory fluid, or ejaculate.
  • Prostate gland . The prostate gland is a walnut-size structure that is located below your bladder and in front of your rectum. The prostate gland contributes additional fluid to the ejaculate. Prostate fluids also help to nourish your sperm. The urethra, which carries the ejaculate to be expelled during orgasm, runs through the center of the prostate gland. Your prostate also converts some of your testosterone into another hormone, called dihydrotestosterone (DHT), which plays a part in sexual development throughout your life. When you're an adult, for example, it's involved in both prostate growth and male pattern baldness.
  • Bulbourethral glands. Also called Cowper's glands, these are pea-size structures located on the sides of the urethra just below your prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. This fluid serves to lubricate the urethra and to neutralize any acidity that may be present due to remaining drops of pee in the urethra.

The entire male reproductive system is dependent on hormones, which are chemicals that control the activity of many different types of cells or organs. There are two types of hormones involved in sexual function and characteristics.

Androgens. This group of sex hormones is found in much higher levels in men/people AMAB. The most common androgen is testosterone. It helps to make sperm and is also responsible for the development of male characteristics, including muscle mass and strength, fat distribution, bone mass, facial hair growth, voice change, and sex drive.

Estrogens. These hormones occur in much higher levels in women or people assigned female at birth. They are responsible for female growth and reproductive development. Men also have estrogen, but in smaller amounts. Low estrogen in men or people AMAB can cause decreased interest in sex and added belly fat. High estrogen levels may cause infertility, larger breasts, and poor erections

In addition to testosterone, the primary hormones involved in the male reproductive system are follicle-stimulating hormone and luteinizing hormone.

Follicle-stimulating hormone is necessary for sperm production (spermatogenesis), and luteinizing hormone stimulates the production of testosterone, which is also needed to make sperm. Both of these hormones are made by your pituitary gland, a pea-size gland that's located in the base of your brain. 


Erectile dysfunction. Symptoms include:

  • Difficulty getting an erection
  • Difficulty maintaining an erection
  • A drop in your desire for sex

Premature ejaculation. The only symptom is ejaculating before you or your partner want, usually before or just after penetration.

Phimosis. This prevents you from being able to pull back your foreskin if you are uncircumcised. Symptoms include:

  • Redness or discoloration
  • Swelling
  • Soreness
  • Pain when you pee
  • Pain when you have an erection and/or during sex

Paraphimosis. This causes your foreskin to get stuck behind the head of your penis. It's a medical emergency that cuts off circulation to the tip of your penis. Symptoms include:

  • Inability to pull your foreskin over the head of your penis to its tip
  • Pain
  • Swelling
  • Discoloration

Epididymitis. This causes inflammation of your epididymis, which is located in your testes. Symptoms include:

  • Swelling, discomfort, or warmth in your scrotum
  • Pain or tenderness in your testicles, often on just one side
  • Painful urination
  • Urgent or frequent need to pee
  • Discharge from your penis
  • Pain or other discomfort in your belly or in the area around your pelvis
  • Blood in your semen

Male infertility. This means you are not able to impregnate your female partner despite having regular, unprotected sex for at least a year.

Peyronie's disease. This causes your penis to curve or bend, usually when you have an erection. Symptoms include:

  • Hard lumps on your penis
  • Pain during sex or when you have an erection
  • A curve in your penis whether or not it's erect
  • Narrowing, shortening, or other changes to the shape of your penis
  • Erectile dysfunction

Sexually transmitted infections (STIs). The symptoms will depend on the specific STI, but they can include:

  • Bumps, warts, or sores on your penis
  • Discharge from your penis
  • Swelling or itching around your penis
  • Pain during sex
  • Pain when you pee
  • Frequent need to pee

Low testosterone (hypogonadism). When your testosterone level drops below normal, the following symptoms can occur:

  • A drop in your sex drive (also called low libido)
  • Fatigue
  • Loss of muscle
  • Irritability
  • Erectile dysfunction
  • Depression

Priapism. This is when your penis stays erect or partially erect for four hours or longer and is not caused by sexual arousal. Other symptoms may include:

  • Your penis shaft is rigid, but the tip of your penis remains soft
  • Pain in your penis that gets worse over time
  • Your penis shaft is erect but not completely rigid

Testicular torsion. This is a medical emergency in which blood flow to your testicles gets cut off. Symptoms include:

  • Painful swelling on one side of your scrotum
  • A lump that you can see on one of your testicles
  • One of your testicles is higher than the other
  • Discoloration in your scrotum, turning it red, purple, brown, or black
  • Nausea and vomiting
  • Pain in your belly (abdomen)
  • More frequent need to pee
  • Fever

Varicocele. This condition causes the veins in your scrotum to enlarge. This can impact your fertility. Typically, no symptoms occur. However, you may notice the following:

  • Dull pain in your testicles or an ache in your scrotum
  • Swollen testicles or scrotum
  • Shrinking of your testicles
  • A small lump above your affected testicle(s)

Hypospadias. In men/people AMAB with this birth defect, the urethra opens on the underside of the penis rather than at the tip of the penis. Symptoms include:

  • Downward curving of your penis
  • Your penis has a hooded appearance because your foreskin only covers the top half of your penis
  • Your pee does not spray normally when you urinate.

Testicular cancer. This uncommon but highly treatable type of cancer has the following symptoms:

  • A lump or swelling in either of your testicles
  • A heavy feeling in your scrotum
  • A dull ache in the lower part of your belly or in your groin
  • A sudden swelling of your scrotum
  • Pain or other discomfort in a testicle or in your scrotum
  • Your breasts enlarge or become tender
  • Back pain

Penile cancer. This rare type of cancer can cause the following symptoms:

  • Some of the skin on your penis thickens or changes color
  • A lump on your penis
  • A bleeding sore (ulcer) on your penis
  • A reddish and velvety rash on your penis
  • Small and crusty bumps on your penis
  • Flat growths that are bluish-brown on your penis
  • Swelling of your penis
  • A smelly discharge coming from under your foreskin

Prostate cancer. You likely won't have symptoms until your prostate cancer has advanced. Symptoms may include:

  • Difficulty peeing, such as a weak, slow stream or peeing more frequently at night
  • Blood in your pee or semen
  • Erectile dysfunction
  • Pain in your hips, back, ribs, and elsewhere, indicating your cancer has spread beyond your prostate
  • Weakness or numbness in your legs or feet
  • Loss of bladder or bowel control
  • Weight loss
  • Fatigue

There's plenty that you can do to keep your reproductive system working normally throughout your life. 

Regular STI testing. Recommendations differ depending on your sexual practices and who you have sex with. Here's what the CDC recommends:

  • Everyone between ages 13 and 64 should be tested at least once for HIV.
  • Sexually active gay, bisexual, and other men/people AMAB who have sex with men should be tested:
    • At least once annually for chlamydia, gonorrhea, and syphilis, and every 3 to 6 months if you have multiple or anonymous partners
    • Once a year or more for HIV
    • At least once a year for hepatitis C if you are HIV positive
  • Those who practice higher risk sex or who share needles should be tested for HIV once a year or more.
  • Everyone who engages in oral or anal sex should discuss testing with their doctor.

Practicing good hygiene. Wash your penis, scrotum, and the surrounding areas to prevent infections. If you have not been circumcised, pull back your foreskin, then clean and dry the head of your penis.

Practicing safe sex. Use condoms when you have sex to help prevent STIs.

Managing chronic health conditions. Many diseases can make it more difficult to have an erection because of their impact on blood flow to your penis and other factors. These conditions include:

  • Type 2 diabetes
  • High blood pressure (hypertension)
  • Heart disease
  • High cholesterol
  • Obesity

Getting the HPV vaccine. This will protect you from infection by human papillomavirus (HPV), which can cause penile cancer, anal cancer, throat cancer, and genital warts. The vaccine is recommended for people ages 9 to 45.

Don't smoke. It not only ups your odds of cancer and heart disease, smoking also contributes to erectile dysfunction.

Do self-checks/exams. Regular checks can reveal any suspicious changes to your penis, testicles, and scrotum, such as swelling or lumps. You may be able to see some changes. You should also feel each of your testicles.

Talk to your doctor about prostate cancer screening to determine if it's right for you. There are risks and benefits associated with screening, making this a complex topic and an individual decision that you can make with help from your doctor.

Get circumcised. Removing your foreskin can lower your risk of urinary tract infections, STIs, and penile cancer. You also won't be at risk of phimosis and paraphimosis.

Maintain a healthy weight. Obesity has been linked to erectile dysfunction. If you lose weight, your ability to get and maintain an erection will rise.

The male reproductive system plays an enormous role in the life of men/people AMAB. It's not only essential for producing new human life. It determines many of your physical characteristics, beginning in childhood. Understanding and protecting its many parts, both internal and external, will help you live a healthy, satisfying life.

What are the 10 parts of the male reproductive system?

They are the following:

  • The penis
  • The testicles
  • The scrotum
  • The epididymis
  • The vas deferens
  • The urethra
  • The seminal vesicles
  • The prostate gland
  • The ejaculatory ducts
  • The bulbourethral (Cowper's) glands

What are the common diseases of the male reproductive system?

Many conditions can affect different parts of the male reproductive system. They include:

  • Erectile dysfunction
  • Testicular cancer
  • Prostate cancer
  • Sexually transmitted infections (STIs)
  • Premature ejaculation
  • Male infertility
  • Priapism

What are some interesting facts about the male reproductive system?

  • All people assigned male at birth have a male reproductive system, but it doesn't come fully function until puberty, which typically starts more than 10 years after birth.
  • Unlike the female reproductive system, much of the male reproductive system is on the outside of the body.
  • The male sexual reproductive system contains elements responsible for more than just sex. For example, the main male sexual hormone -- testosterone -- not only puts hair on your chest and elsewhere on your body, it also plays a part in baldness.