If your enamel is worn away, your dentin and its tubules can be exposed.

如果你的牙釉质被磨掉了，你的牙本质和它的小管就会暴露出来。

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

睾酮的目标是小管中最外层的细胞，称为精原细胞。

It contains microscopic, fluid-filled tubules that run from the pulp to the underside of the enamel.

它包含微小的、充的小管，从牙髓一直到牙釉质下层。

Beneath that is the medulla, a set of cone-shaped masses of tissue that secrete urine into tiny sac-like tubules.

髓质下面是一组锥形组织，将尿泌到微小的囊状小管中。

ADH affects the last two-thirds of these tubes, called the distal convoluted tubule and the collecting ducts.

ADH作用于这些小管的终末2/3部，即远曲小管和集合管。

Each one is divided into about 250 sections, called lobules, which are loaded with tightly-coiled seminiferous tubules.

每一个都被成大约 250 个部，称为小叶，其中紧密盘绕的生精小管。

As the filtrate leaves the Bowman's capsule it flows into the renal tubule, which is surrounded by the peritubular capillaries.

滤离开肾小囊后流入肾小管，后者被管周毛细血管网包围。

These tubules are the sperm factories, made of a stratified epithelium surrounding a central fluid-filled lumen.

这些小管是精子工厂，由围绕充的中央管腔的层上皮组成。

And this sperm-making work is supported by cells throughout and around the tubules.

这种精子制造工作是由遍布小管及其周围的细胞支持的。

Typically intrarenal AKI's due to damage to the tubules, the glomerulus, or the interstitium —the space between tubules.

通常，肾性AKI是由于肾小管、肾小球或间质空间（肾小管间的空间）损坏所致。

Now, obviously, if sperm are going to get anything accomplished, they have to leave the seminiferous tubules that made them.

现在，很明显，如果精子想要完成任何事情，它们必须离开制造它们的生精小管。

It's called a cast because it stays in essentially the same cylindrical shape as the tubule.

它被称为管型，是因为它基本上与小管保持相同的圆柱形状。

So, let's trace the whole process, starting at the top, with the proximal convoluted tubule or PCT.

所以，让我们追踪整个过程，从顶部开始，用近端卷曲小管或 PCT。

And this is showing us the digestive tubules of these animals.

这向我们展示了这些动物的消化管。

Macula densa cells are located in the distal convoluted tubule and they can sense when levels of sodium and chloride are low.

致密斑位于远曲小管，可以感受到钠和氯水平降低。

But the other kind — the type B's — get pushed down the tubule toward the lumen, and turn into primary spermatocytes.

但是另一种，B 型，则是沿细管进入管腔，然后变成初级精母细胞。

Some substances are removed from blood through the peritubular capillary network into the distal convoluted tubule or collecting duct.

有些物质通过管周毛细血管网从血中移出，进入远曲小管或集合管。

But in this case, the sperm develop on the outer edge of the tubule, and progress inward toward the lumen.

但是在这种情况下，精子在小管的外缘发育，并向内腔前进。

Within each kidney, there are about 1 million nephrons, and each nephron is made up of a renal corpuscle and a renal tubule.

每个肾约有100万个肾单位，每个肾单位由肾小、肾小管组成。

All this twisting might make the tubule look, like, super inefficient, but it actually serves an important purpose, as you might expect.

所有这些扭曲可能会让小管看起来超级低效，但它实际上有一个重要的目的，正如你所料。