An overview
The reproductive system is the group of organs that makes gametes (sex cells) and brings them together so that a new individual can form. In humans the male and female systems are different in structure but complementary in function: the male delivers sperm, the female produces ova, protects the developing offspring and gives birth.
The male reproductive system
The paired testes sit in the scrotum, a skin sac that hangs outside the body cavity. This keeps the testes a few degrees below core body temperature, which is needed for healthy sperm formation. Inside each testis, tightly coiled seminiferous tubules produce sperm and interstitial cells release the hormone testosterone. Mature sperm are stored in the epididymis, then travel along the vas deferens (sperm duct) during ejaculation.
- The seminal vesicles and prostate gland add an alkaline, fructose-rich fluid; sperm plus this fluid together make up semen.
- The urethra runs through the penis and carries either urine or semen, but never both at the same time.
The female reproductive system
The two ovaries produce ova and secrete the hormones oestrogen and progesterone. Each month an ovum is released and swept into the funnel of an oviduct (fallopian tube), where fertilisation normally takes place. The uterus is a muscular organ lined by the endometrium, in which a fertilised egg implants and develops. Its lower narrow neck, the cervix, opens into the vagina, which receives sperm and forms the birth canal.
Example
During ejaculation, sperm made in the seminiferous tubules pass from the epididymis, along the vas deferens, mix with fluid from the seminal vesicles and prostate to form semen, and leave the body through the urethra.
Remember
Testes = sperm + testosterone; ovaries = ova + oestrogen and progesterone. Fertilisation happens in the oviduct, not in the uterus.