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Human Body Study

Testes

The paired male gonads, held in the scrotum outside the body. They produce sperm and the hormone testosterone.

Male reproductive system Front-view schematic showing the testes, duct system, accessory glands and penis; each labelled part links to its article. Male reproductive system bladder prostate Accessory glands the seminal vesicles, prostate, and bulbourethralglands, which produce the fluid of semen. Duct system the epididymis (where sperm mature and arestored) and the vas deferens (which carriessperm onward). Penis the organ of delivery; its urethra is sharedwith the urinary system. Testes produce sperm and the hormone testosterone;held in the scrotum, outside the body, for theslightly cooler temperature sperm need. Male reproductive system — schematic front view, not to scale.

Structure

Section titled “Structure”
  • Seminiferous tubules — tightly coiled tubes where sperm are made.
  • Interstitial (Leydig) cells — between the tubules; produce testosterone.
  • Scrotum — the loose skin sac that houses both testes, keeping them slightly cooler than the body core.

What they do

Section titled “What they do”
  • Spermatogenesis — produce sperm continuously from puberty onward.
  • Testosterone production — drives male sexual development and maintains the reproductive system.

Key idea

Section titled “Key idea”

Sperm production requires a temperature a few degrees below body core, which is why the testes hang outside the body. The scrotum even contracts in cold and relaxes in heat to keep them at the right temperature. See also the HPG axis.