What are the testicles?

The testicles (also called testes) are two egg-shaped organs that sit inside the scrotum, the loose pouch of skin under the penis. Their two main jobs are:

Making sperm (cells needed to fertilize an egg).
Producing testosterone (the main male sex hormone), which drives many changes during puberty.

Basic structure

Testes: the two main glands that produce sperm and hormones.
Epididymis: a soft, coiled tube on the back/upper part of each testicle where sperm mature and are stored.
Vas deferens: the tube that carries sperm from the epididymis toward the urethra during ejaculation.
Scrotum: the skin pouch that holds and protects the testes and helps control temperature (sperm need a slightly cooler temperature than body temperature).

What happens during puberty?

At puberty (which often starts between about 9 and 16), the testicles grow and start producing more testosterone. Typical changes include:

Growth of the testicles and penis.
Growth of pubic, underarm and facial hair.
Voice deepening and increased muscle mass.
Onset of erections and ejaculation; production of sperm begins (fertility may follow later in puberty).

How your testicles should feel (what’s normal)

Each testicle is usually smooth, firm, and egg-shaped. They should not be rock-hard or extremely soft.
It’s normal for one testicle (often the left) to hang slightly lower than the other.
The epididymis feels like a soft, rope-like structure along the back/top edge of the testicle — that is normal.

How to do a monthly testicular self-exam (simple, private, quick)

Do it after a warm shower or bath so the scrotal skin is relaxed.
Stand in front of a mirror and look for any swelling on the skin of the scrotum.
Hold one testicle at a time with both hands. Put your index and middle fingers under and your thumbs on top.
Gently roll the testicle between your fingers and thumbs, feeling for lumps, bumps, or changes. Don’t squeeze hard.
Locate the epididymis (soft tube at the back) so you don’t mistake it for a lump.
Do the other testicle the same way. It should only take a few minutes total.
Check once a month so you become familiar with how yours normally feel.

Things that are cause for concern (see a doctor)

Some signs mean you should get medical help right away; others should be checked within a few days to a week.

Go to the emergency room or urgent care now if:

You have sudden, severe testicular pain or a very swollen, red scrotum (this could be testicular torsion, which needs immediate treatment).
Pain accompanied by fever or nausea/vomiting.

Make a regular appointment or see a doctor soon if you notice:

A painless lump or hard area on the testicle.
Any persistent swelling, heaviness, or changes in size of a testicle.
Persistent or recurring pain, or blood in semen/urine.
Changes that worry you — it’s better to get them checked than to ignore them.

Common conditions (brief)

Testicular torsion — twisted spermatic cord: sudden pain, emergency.
Epididymitis — inflammation/infection of the epididymis: pain, sometimes fever, usually treatable with antibiotics.
Hydrocele — fluid around the testicle: usually painless swelling.
Varicocele — enlarged veins in the scrotum: may cause a heavy feeling or affect fertility.
Testicular cancer — uncommon but most often affects teens and young men (15–35). It often causes a painless lump and is highly treatable when found early.

How to take care of your testicles

Practice good hygiene: wash the scrotum and penis with mild soap and water regularly.
Wear protective gear (athletic cup) for contact sports.
Use condoms and practice safe sex to reduce the risk of STIs; talk to a doctor about testing if you’re sexually active.
If you’re worried about fertility, medicines, surgeries, and other options exist — talk to a healthcare professional.

Talking to a doctor or someone you trust

It’s normal to feel embarrassed, but health professionals are used to this topic and will treat you respectfully and confidentially. If you’re under 18 and worried about privacy rules in your area, ask about what the clinic’s policy is on confidentiality for teens.

Summary

The testicles make sperm and testosterone and change during puberty. Getting to know how your testicles normally look and feel with a monthly self-exam helps you spot changes early. Seek urgent care for sudden severe pain or rapid swelling. For lumps, ongoing pain, or any worries, see a healthcare provider — most problems are treatable, and early care matters.

If you want, I can walk you through a self-exam step-by-step or list nearby resources for confidential teen health care in your area. Do you want that?