作者:Cathy Huynh 11 年以前
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sperm are formed inside clusters of tiny coiled tubes which are the testes
Characteristics: deep voice, broad shoulders, & sperm production
function: keeps testes 2 to 3 degrees C below regular body temp. for sperm production
external pouch of skin that houses the testes
leaves through penis through the urethra (tube in the penis)
muscles in penis contract so urine & semen don't mix
contains nutrients that sperm uses as energy
allows the sperm to swim