Teratoma is a tumor with tissue or organ components resembling normal derivatives of more than one germ layer. The tissues of a teratoma, although normal in themselves, may be quite different from surrounding tissues and may be highly disparate; teratomas may contain hair, teeth, bone and, very rarely, more complex organs or processes such as brain matter, eyes, torso, and hands, feet, or other limbs. Ovarian teratoma is a type of germ cell tumour. Cancerous teratomas are rare, and usually affect girls and young women up to their early 20s. By: https://youtu.be/Hj9xdL5Pxzo