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💡 Halving for the future
Body cells carry 46 chromosomes, but a sperm or egg carries just 23 — so that when they join, the count is perfect again.
How are gametes made (gametogenesis)?
Gametogenesis
The making of gametes by meiosis in the testes and ovaries; sperm and eggs carry 23 chromosomes. Males: many sperm; females: one egg
- The formation of gametes is called gametogenesis ; it takes place in the testes and ovaries.
- Gametes are formed by meiosis , so sperm and eggs carry only 23 chromosomes (body cells have 46).
- In males it makes many tiny motile sperm ; in females it makes a single large egg .
| Feature | Sperm | Egg |
|---|---|---|
| Size | Very small | Large |
| Number produced | Millions | Few |
| Stored nutrients | Absent | Present |
| Motility | Actively motile | Non-motile |
✅ Test Yourself
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Why does the scrotum hang outside the body?
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It keeps the testes slightly cooler than body temperature, as sperm formation needs. -
Which tube carries sperm from the testes to the urethra?
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The vas deferens . -
Where does fertilisation usually take place in a woman?
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In the oviduct (fallopian tube). -
Compare the number of sperm and eggs produced.
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Sperm are produced in millions; eggs are few, and usually one matures each month.
Important Definitions
- Gametogenesis — the formation of gametes by meiosis — sperm in the testes, eggs in the ovaries.
