The tiny oocyte moves along the fallopian tube.

微小的卵母胞沿输卵管运动。

But right around birth, the oocytes stop developing — they get stuck in the first stage of meiosis.

但是在出生的时候，卵母胞停止发育——它们卡在减数分裂的第阶段。

The primary oocyte has 46 chromosomes, but eventually it has to turn into a gamete with only 23 chromosomes.

初级卵母胞有46条染色体，但是最终会变成只有23条染色体的配子。

And, each follicle is made up of a germ cell, also known as an oocyte, which is the immature egg.

每个卵泡个生殖胞组成，也就是卵母胞，就是未成熟的卵子。

The truth is, most sperm never reach an oocyte.

事实是，大多数精子永远无法到达卵母胞。

To do this, the primary oocytes have to complete meiosis 1, and in a person's lifetime only about 400 successfully do that.

要变成配子就必须要经历第次减数分裂，而个人的生中大概只有400个初级卵母胞可以做到。

Those enzymes are the key to getting through the oocyte's protective outer layers.

这些酶是穿过卵母胞保护外层的关键。

This inner machinery includes two ovaries stocked with thousands of tiny sacks called follicles that each contain one oocyte, an unfertilized egg cell.

这套内部机制包含两个卵巢，卵巢内存有成千上万的微小袋子，叫做卵泡，每个卵泡内含有个卵母胞，即未受精卵胞。

Each primordial follicle has a single immature sex cell called the primary oocyte at the core, and a layer of follicular cells surrounds this.

每个始基卵泡中心有个未成熟的生殖胞，叫做初级卵母胞，被卵泡胞包裹。

Meanwhile, the primordial follicle turns into a primary follicle, meaning that the follicular cells that surrounding the primary oocyte develop into granulosa cells.

与此同时，包围初级卵母胞的滤泡胞分化为颗粒胞，使始基卵泡变为初级卵泡。

The first stage lasts from infancy to puberty, and during this stage the primary oocyte remains stuck in the prophase step of meiosis 1.

第阶段从婴儿期到青春期，初级卵母胞还停留在第次减数分裂的前期。

After ovulation, the secondary oocyte makes a very quick journey through the peritoneal space and lands in the fallopian tube.

排卵之后，次级卵母胞会快速地通过腹膜，最后落入输卵管。

Once it's past that, it runs into the zona pellucida, a layer of glycoprotein that covers the oocyte's plasma membrane.

旦过了这个阶段，它就进入透明带，覆盖卵母胞质膜的层糖蛋白。

This tells the secondary oocyte to get ready to complete its second meiotic division.

这告诉次级卵母胞准备完成第二次减数分裂。

These two phases are separated by ovulation, which is when the follicle ruptures and releases an oocyte that is ready to be fertilized.

这两个阶段被排卵分开，排卵即：卵母胞被卵泡排出，准备好受精。

The secondary oocyte stops in metaphase of meiosis 2, and waits for fertilization as the menstrual cycle transitions into the luteal phase.

次级卵泡会在第二次减数分裂中期停止分裂，并且在卵泡期向黄体期转换的时候等待受精。

That's when the nearly 2 centimeter sized follicle ruptures and releases the tiny secondary oocyte into the fallopian tube.

此时将近2cm的卵泡破裂，向输卵管释放出次级卵泡。

In fact, sometimes only a dozen or so of the original millions make it through all those trials to actually reach an oocyte.

事实上，有时候几百万个卵母胞中只有打左右通过了所有这些试验最终得到了卵母胞。

But before that it has to weave through the granulosa cells that form the oocyte's outermost layer, known as the corona radiata.

但在此之前，它必须穿过形成卵母胞最外层的颗粒胞，称为辐射日冕。

You'll remember that during ovulation, about once a month, an ovary releases a secondary oocyte that heads down the fallopian tube and toward the uterus.

你会记得在排卵期，大约个月次，卵巢释放个次级卵母胞，该卵母胞沿着输卵管流向子宫。