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.

第三种亚型是绒毛膜癌，它是由转化成合体滋养细胞的生殖细胞组成，合体滋养细胞帮助形成胎盘。

The four major types of germ cell tumors are: fetal teratomas, both mature cystic and immature teratomas; yolk sac tumors, or endodermal sinus tumor, choriocarcinoma or placental tissue tumors and finally dysgerminomas or oocyte tumors.

4种卵巢细胞癌如下：畸胎瘤，包括成熟囊性畸胎瘤和未成熟畸胎瘤；卵黄囊瘤，又叫内胚窦瘤；绒毛膜癌，又叫胎盘组织肿瘤；最后是无性细胞瘤，又叫卵母细胞瘤。