The targets of the testosterone are the outermost cells in the tubules, called spermatogonia.

睾酮的小管中最外层的，称为精。

But when puberty starts, the testosterone causes them to divide differently — instead of splitting into two identical spermatagonia cells, they begin producing two distinct spermatogonia.

但当青春期开始时，睾丸激素导致它们以不同的方式裂——而不裂成两个相同的精，它们开始产生两个不同的精。

And considering how many spermatogonia are continuously dividing into spermatocytes, it's easy to see how a mature male can crank out 1500 sperm a second.

考虑到有多少精不断裂成精母，很容易看出一个成熟的男性如何每秒产生 1500 个精子的。

And actually, they've been doing that all along — even before puberty. Throughout childhood, a spermatogonia cell uses mitosis to continuously divide into two identical daughter cells.

事实上，它们一直都在这样做——甚至在青春期之前。在整个童年时期，精通过有丝裂不断裂成两个相同的子。

One type of daughter cell — known as a type A cell — stays up near the basal lamina and just keeps dividing, so you never run out of spermatogonia.

有一种子——也就众所周知的 A 型——会待在基底层附近并不断裂，所以精永远不会耗尽。