性器官-男性性器官
The Sex Organs - The Male Sex Organs

内部性器官：睾丸

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精子的产生
睾丸被分隔出数百个小小的间隔，其内含有不比头发丝粗多少的、紧密蟠曲的细小管道。在这些管道（称为生精小管）里，是精子产生（称为精子发生）的场所。当男性长到青春期，精子产生就开始了，自此会终其一生。精子产生有三个步骤：
 

The Internal Sex Organs: The Testicles

The Production of Sperm
A testicle is composed of hundreds of small compartments which contain tightly coiled tubes not much thicker than a hair. Inside these tubes (called seminiferous tubules) the process of sperm production (called spermatogenesis) takes place. This process begins when the male reaches puberty and continues without interruption throughout his life. The production of sperm proceeds in three steps.