Island Sexual Health Society Be informed, not surprised

The Penis, Scrotum, testicles and more

The biological male reproductive/sexual system is made up of the organs that allow a male to:

  • have and enjoy sexual intercourse
  • produce sperm (male sex cells)
  • fertilize ova (eggs) with sperm

The sexual organs  are partly visible and partly hidden within the body.

Internal sex organs


  • Oval-shaped glands that are about 4cm in length and 3cm in width
  • The testes make millions of sperm every day and also secrete the male sex hormones
  • The testes are sensitive to touch

Male body diagram of testes and scrotum


  • Highly coiled tube that lies around the back of the testicle
  • Sperm are passed to the epididymis from the testes where they are made
  • Sperm is stored in the epididymis for about 20 days until they are mature
  • Once mature the sperm move to the vas deferens
  • The testes and epididymis form each testicle

Male body part: epididymis diagram

Vas deferens

  • About 45cm (18 inches) long and runs from the epididymis to the urethra
  • It carries the sperm from the testes to the urethra and stores it prior to ejaculation
  • The sperm become mixed with secretions along the way and form semen

Diagram of the vas deferens in relation to penis


  • Tube that links the vas deferens to the outside
  • Also runs from the bladder, serving both the urinary and reproductive systems

male body part diagram: urethra

Seminal vesicles

  • Lie behind the bladder and produce the secretion which makes up 60% of the semen
  • These secretions contain fructose which acts as a fuel for the sperm

pullout diagram of seminal vesicle

Prostate gland

  • Is just below the bladder and is about the size of a chestnut
  • Makes secretions which make up about 30% of the semen
  • These secretions make the vagina less acidic so that sperm can survive better

Prostate gland diagram inside male body

External  sexual organs

male body part close up diagram of penis


  • Consists of the shaft and the head (called the glans)
  • The glans, the corona (the rim of the glans) and the frenulum (tissue that links the underside of the glans and the shaft) are very sensitive and play a big role in sexual pleasure
  • Some men are circumcised which means that the foreskin (skin covering the head of the penis) has been cut away; on an uncircumcised penis the loose foreskin is still covering the head of the penis but can be slid back
  • Inside the penis is the urethra, carrying sperm and urine to the outside of the body
  • During sexual arousal, the penis becomes filled with blood and becomes erect
  • The average flaccid penis is 8-10cm long and the average erect penis is 15cm long
  • There is considerable variation in the size of a flaccid penis but not very much variation in the size of an erect penis
  • During ejaculation, between 300 and 500 million sperm are released


  • The two testes are contained in the scrotum outside the body, in order to maintain the right temperature for sperm to be produced