Reproduction: How Life Continues
Human reproductive systems
Learn the parts of the human reproductive system.
During adolescence, the reproductive organs mature and begin making gametes: sperm in males and eggs in females. This is a normal part of growing up.
The male reproductive system:
- Two testes make sperm. They sit in a pouch called the scrotum, outside the body, because making sperm needs a temperature slightly cooler than the body.
- The testes also make a hormone that controls sperm making and the changes of puberty in boys.
- Sperm travel along the vas deferens to the urethra, a tube shared by urine and sperm.
- The seminal vesicles and prostate add fluids that nourish the sperm.
Each sperm has a head with the genetic material and a tail to swim.
The female reproductive system:
- Two ovaries make eggs and hormones.
- The oviducts (fallopian tubes) link the ovaries to the uterus, where a baby grows.
- The uterus opens into the vagina through the cervix.
Making gametes (gametogenesis) happens in the testes and ovaries by meiosis. Body cells have 46 chromosomes; sperm and eggs have 23. When they join, the zygote has 46 again.
Sperm and egg compared (Table 11.5):
| Sperm | Egg | |
|---|---|---|
| Size | Very small | Large |
| How many | Millions | Few |
| Stored food | None | Yes |
| Movement | Swims actively | Does not move by itself |
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