Ovarian cancer is a cancer that forms in or on an ovary. Adult females have a single functional ovary and uterus. The fallopian tube allows passage of an egg from the ovary to the uterus. This includes those who have polycystic ovary syndrome. It is also used in the treatment of polycystic ovary syndrome. The ER is expressed in specific tissues including the ovary, uterus and breast. Carcinoid tumors may rarely arise from the ovary or thymus. It too occurs in both the ovary and testis. Usually, this includes a unilateral salpingo-oophorectomy, removal of a single affected ovary and Fallopian tube. Fertilization occurs in the ampulla, the section of the oviduct that curves around the ovary. One or several follicles of the ovary start to grow. Angiosperms produce seeds enclosed in a structure such as a carpel or an ovary. It has numerous stamens inserted below the ovary. Estradiol appears necessary to maintain oocytes in the ovary. Addition of chemotherapy may be required for more aggressive tumors confined to the ovary.