Assigned Male at Birth

Anatomy | Puberty


  • Penis: The penis is an organ made of erectile tissue and blood vessels, and it is full of nerve endings. During arousal, the penis fills with flood, making it get longer, wider, and firm (erect or hard).
  • Testicles: People with a penis typically have two testicles (or testes) that make sperm and the hormone testosterone. Once a person hits puberty, the testicles will make millions of sperm every day.
  • Scrotum: The scrotum is a protective pouch that holds the testicles outside the body. It helps keep the testicles cooler than the temperature inside the body. The temperature inside the body is too warm for sperm to be made.
  • Urethra: The urethra is a thin tube that goes down the center of the penis. It connects to the bladder and vas deferens. During ejaculation, the sperm travels out of the penis through the urethra.
  • Urethral (Urinary) Opening: This is the opening at the end of the penis. During an orgasm, semen leaves the urethra through the urethral opening. This is called ejaculation (“cumming”). Urine (pee) also comes out of the urethral opening, but this cannot happen at the same time ejaculation is taking place.
  • Epididymis: Inside the scrotum, there is an epididymis on top of each testicle. Sperm mature and are stored there until they are able to travel up the tubes and out the penis.
  • Prostate: The prostate makes a thin, milky fluid that mixes with sperm and is part of semen. Prostate gland fluid helps sperm move and keeps the sperm healthy.
  • Seminal Vesicle: Seminal vesicles make a thick fluid that mixes with sperm and prostate gland fluid to make semen. This fluid helps sperm move and keeps them healthy. 
  • Vas Deferens: The vas deferens are tubes connected to each epididymis. The sperm leave the epididymis through the vas deferens, where it meets with fluids from the prostate gland and seminal vesicle to create semen. The vas deferens then connect to the urethra for semen to leave the body.
  • Bulbourethral Gland (Cowper’s Gland): There are typically two cowper’s glands, located next to the urethra. These glands create a clear, slippery pre-ejaculatory fluid (pre-cum) that cleans out the urethra to make way for the sperm. During sexual arousal, this fluid starts to be released before ejaculation.

When you’re between 9 and 14 years old, you’ll start going through puberty. During this time, the body changes from a child to a young adult. Puberty happens earlier for some than others, but eventually everyone experiences it.

This won’t happen all at once; changes will happen slowly over a few years and will include physical, emotional, and social changes.

  • Voice gets deeper and Adam’s apple (bump in your throat) might get bigger
  • Penis and testicles get bigger
  • Hair may grow on face, chest, and back
  • Chest and shoulders get broader
  • Some have swelling around the nipples (it can look like the start of breasts but usually goes away)
  • May get acne (zits or pimples)
  • Starts to sweat more, and may have body odor
  • Grows hair in your armpits, on your arms and legs, and around your genitals
  • May have stronger/more intense emotions (including mood swings)
  • May experience more sexual thoughts and urges

Puberty can be a confusing time. Some feel like there’s a lot happening that’s out of their control. You don’t have to go through it alone. Talking with an adult you trust may help you sort out your feelings.

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