http://www.ck12.org Chapter 1. Human Biology
1.70 Human Egg Cells
- Explain what eggs are and how they are produced.
How is egg different from sperm?
Egg and sperm are both gametes, or reproductive cells. Notice how different they are, however. The egg is much
larger than the sperm. The egg also does not have a tail. And the female only releases one egg at time, while the
male releases millions of sperm at a time.
Eggs and Egg Production
When a baby girl is born, her ovaries contain all of the eggs they will ever produce. But these eggs are not fully
developed. They develop only after she starts having menstrual periods at about age 12 or 13. Just one egg develops
each month. A woman will release an egg once each month until she is in her 40s.
Eggs
Eggs are very big cells. In fact, they are the biggest cells in the human body. An egg is about 30 times as wide as a
sperm cell!
You can even see an egg cell without a microscope. Like a sperm cell, the egg contains a nucleus with half the
number of chromosomes as other body cells. Unlike a sperm cell, the egg contains a lot ofcytoplasm, the contents
of the cell, which is why it is so big. The egg also does not have a tail.
Egg Production
Egg production takes place in the ovaries. It takes several steps to make an egg: