sábado, 8 de junho de 2013

Reproductive System

Both males and females have gonads, which are structures that produce reproductive cells -- sperm and and eggs. These cells are called gametes.
The gonads also produce sex hormones, which are chemical messengers that control the development and function of the reproductive system.
The structures that play a direct role in reproduction are called the primary sex characteristics. The ones that don't play a directly role are called secondary sex characteristics.


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