The Embryonal Carcinoma is one of the several types of testicular (or ovarian) germ cell tumors, which also inclue the seminoma (dysgerminoma in ovary), teratoma, Endodermal sinus tumor and choriocarcinoma. Forming from a malignant germ cell tumor, the embryonal carcinoma is a reproductive cell gone out of control. Like any cancer, it grows with its cells dividing rapidly and indefinitely. The embryonal carcinoma can spread up the epididymis to the vas deferens and spread to the rest of the body, including the lymph nodes that run along the aorta. It is only in the testicular germ cells that this carcinoma develops.