Ovarian germ cell tumors

With germ cell ovarian cancer, germ cell refers to the precursor cells that develop into eggs, ovarian refers to ovary which is where the germ cells live, of which there are two that sit on either side of the uterus.

So, a germ cell ovarian cancer refers to situations where these precursor germ cells become cancerous and form tumors.

During fetal development, the entire body derives from three layers, called germ layers, the ectoderm, mesoderm, and endoderm.

These germ layers are made of germ cells, and the germ cells migrate out and differentiate into all of the different types of tissues, for example some ectodermal germ cells become cells of the brain and spinal cord, some mesodermal form bone and muscle, and some endodermal cells become cells in the gastrointestinal tract.

Some very special germ cells, however, remain as germ cells - meaning that they don’t differentiate, they remain pluripotent, meaning that unlike the cells that differentiate these germ cells retain their ability to turn into other cell types. They’re like ancient little shape-shifters.

Normally, during development these germ cells head to the ovary in women or testicle in men where they remain for decades, eventually developing into eggs or sperm, respectively.

Now, if those germ cells in the ovaries start to divide uncontrollably, it can either form a benign tumor which means that it does not invade nearby tissue or spread to other parts of the body, or it can be a malignant tumor which means that it can both invade and spread to other tissues.

Compared with benign tumor cells, malignant tumor cells have key features like not having a clearly defined border or like a slightly less organized nuclei.

There are four types of germ cell tumors and each type is named after the type of cell that these pluripotent germ cells develop into.

The first, are teratomas, terato means monster and oma is a tumor.

So teratomas are monster tumors, and they are called that because they contain all kinds of different tissues, including hair, eyes, teeth, bone and neurons - like a Frankenstein that’s got bits of this and that stitched together.

Now, there are two types of teratomas, the first are mature cystic teratomas, which are the most common ovarian tumors in young women and are formed from tissue that comes from any of the three germ layers.

One example, is a struma ovarii tumor which is made up of only thyroid tissue and can release thyroid hormone which leads to hyperthyroidism.

The other type are immature teratomas, and they develop specifically from neuroectoderm cells - which come from the ectoderm layer.

Immature teratomas tend to be malignant and metastasize quickly.

The second subtype is a yolk sac tumor, also called an endodermal sinus tumor, and it’s made of germ cells that differentiate into yolk sac tissue.

These are the most common germ cell tumor in children, and the tumors can be very aggressive.

Under the microscope, they form Schiller-Duval bodies which are rings of cells around a central blood vessel.

The third subtype is a choriocarcinoma and it’s made of germ cells that turn into syncytiotrophoblast cells which are the ones that help form the placenta.

These tumors are usually small, bleed easily, and often spread beyond the ovaries.

The syncytiotrophoblast cells secrete high levels of the hormone β-hCG, and that can cause ovarian cysts to form.

The fourth subtype is a dysgerminoma and it’s made of germ cells that turn into oocytes, which is the normal pattern, but then they start to grow uncontrollably.