NCI Dictionary of Cancer Terms

The NCI Dictionary of Cancer Terms features 8,351 terms related to cancer and medicine.

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ovarian follicle
(oh-VAYR-ee-un FAH-lih-kul)
A small, fluid-filled sac in the ovary that contains one immature egg. There are thousands of follicles in the ovaries. When an egg matures during a woman’s menstrual cycle, the follicle breaks open and releases the egg from the ovary for possible fertilization (the process by which an egg combines with sperm to form an embryo). Ovarian follicles may sometimes be checked to help diagnose and treat infertility.