Sperm

What is human sperm?

Sperm are tadpole-shaped microscopic male sex cells. In humans, when a sperm cell joins with (conception or fertilization) a female sex cell (ovum or egg cell), the fetal development process begins. This often happens after vaginal intercourse. But it can also occur through assisted reproductive technologies, such as in vitro fertilization (IVF).

People assigned male at birth (AMAB) start producing sperm around puberty— usually between 10 and 12 years old. But people AMAB can produce sperm throughout their lives.

Other names for sperm include:

• Male reproductive cells.
• Gametes.
• Spermatozoa (singular spermatozoon).

What does sperm do for men?

Sperm’s only function is to fertilize female sex cells.

Not ejaculating or releasing semen (the sticky liquid that contains sperm cells) won’t hurt you or cause any problems. Your body absorbs any sperm you don’t release.

How much sperm is in semen?

A typical sperm count may range from 15 million to more than 200 million per milliliter of semen (about 0.2 teaspoons).

A low sperm count (oligospermia) is less than 15 million sperm per milliliter of semen.

What does sperm do in a woman?

After unprotected vaginal intercourse, sperm cells travel through the vagina, cervix, uterus and eventually fallopian tubes. The immune system recognizes sperm as foreign invaders and mobilizes to kill the sperm. If any surviving sperm make it to the fallopian tubes, they’ll try to penetrate the egg cell.

How long can sperm live inside the body?

Sperm can stay alive within the female reproductive system for up to five days.

Unejaculated sperm can stay alive in your testicles for about 2.5 months. Around this time, sperm cells die, and your body reabsorbs them.

How long does sperm live outside the body?

It depends. Sperm can live up to an hour outside your body in a room temperature environment — 68 degrees Fahrenheit (20 degrees Celsius). Exposure to different temperatures can kill sperm quickly.

If you bank your sperm, it can survive for decades as long as the freezing conditions remain the same.

Where is sperm produced?

Tiny tubes in your testicles (seminiferous tubes) produce sperm. During ejaculation, sperm:

• Exit your testicles.
• Travel to a tube at the back of your testicles (epididymis).
• Enter a coiled tube (vas deferens).
• Travel through the prostate gland.
• Eventually enter the urethra before releasing from the hole at the tip of your penis (urethral meatus).

What are the parts of sperm?

The three main parts of a sperm cell include:

• Head. The sperm head contains DNA. In healthy sperm, the head comes to a slight point, like an almond. A cap (acrosome) covers the head and contains enzymes. The head’s almond shape and the acrosome enzymes help sperm penetrate an egg cell.
• Midpiece (neck). The midpiece contains mitochondria (my-toh-KON-dree-uh), which create energy in your cells. They supply energy for the tail.
• Tail (flagellum). The tail is the longest part of a sperm cell. It moves in a corkscrew-like motion to move sperm forward and help penetrate an egg cell.

What is sperm morphology?

Sperm morphology is the shape of sperm. Specifically, it refers to:

• Head shape and size.
• How the midpiece looks.
• The tail’s structure.

Healthy morphology allows sperm to swim strongly in a straight line.

Examples of abnormal sperm morphology include:

• No sperm head (acephalic sperm).
• Small sperm head (microcephaly).
• Large sperm head (macrocephaly).
• Extra sperm head (double sperm head or duplicate sperm).
• Lack of tail (acaudate sperm).
• Bent or crooked tail.
• Coiled tail.
• Short tail (dysplasia of fibrous sheath sperm).

What conditions affect sperm?

Sperm problems can cause male infertility. Many things can affect your sperm’s health or their ability to travel. But you may not be aware that something is affecting your sperm unless you and your partner are having difficulty getting pregnant. Conditions that may affect your sperm health include:

Varicoceles

Varicoceles are swollen veins in your scrotum. Blood builds up in the veins and increases the temperature inside your scrotum, which may affect sperm growth.

Testicular trauma

Testicular trauma can damage your testicles and affect their ability to produce sperm.

Certain sexually transmitted infections

Some sexually transmitted infections (STIs), including chlamydia and gonorrhea, can harm your sperm.

Certain medications

Certain medications may have side effects that affect your sperm quality. These include:

• Flutamide and bicalutamide. These medications treat prostate cancer.
• Spironolactone. This treats high blood pressure (hypertension) and heart failure.

Testosterone replacement therapy also causes your body to stop producing sperm. It comes in many forms, including:

• Injections.
• Capsules.
• Patches.
• Pellets.
• Skin gels.

Environmental factors

Drinking alcohol and smoking or vaping tobacco or marijuana can affect sperm count and quality.

Long-lasting heat exposure can also damage your sperm. This may include spending time in saunas or bathtubs. Sitting down in a chair or wheelchair for long periods can also increase the temperature of your testicles.

Antisperm antibodies

Your immune system mistakenly identifies sperm as a foreign invader and sends antibodies to kill it.

What are sperm disorders?

Sperm disorders can affect the quality and amount of sperm you produce. They include:

• Oligospermia. This is a low sperm count — fewer than 15 million sperm per milliliter of semen.
• Azoospermia. There’s no sperm in your semen. Azoospermia may occur when something blocks the tubes in your reproductive system.
• Teratospermia. You have a higher concentration of abnormal sperm in your semen. Abnormal sperm morphology can affect sperm’s ability to travel and penetrate an egg cell.

What are common tests to check the health of sperm?

A semen analysis is the best way for a healthcare provider to analyze your:

• Sperm count.
• Sperm shape.
• Sperm activity (motility).

You may produce a semen sample at a fertility clinic, lab or at home. If you produce your sample at home, you must bring your sample to a clinic or lab quickly — usually within an hour.

How can I improve my sperm quality?

The following tips may help you improve your sperm quality:

• Quitting smoking.
• Limiting your alcohol consumption.
• Eating lots of fruits and veggies.
• Maintaining a healthy weight for you.
• Increasing your physical activity.
• Managing your stress.
• Using protection — including condoms, female condoms and dental dams — during sexual intercourse to help protect yourself from STIs.

How much sperm can get me pregnant?

It only takes one sperm cell to get pregnant. But tens to hundreds of millions of sperm release during ejaculation.

A note from Cleveland Clinic

Sperm have one goal: fertilize an egg cell to pass on your DNA. You may not think too much about your sperm unless you have difficulties getting pregnant. But if you and your partner have infertility problems, a healthcare provider will order tests to analyze your sperm and determine how many you have, as well as their shape and activity levels. You can help promote sperm health by quitting smoking, drinking alcohol in moderation, being physically active and protecting yourself from STIs.