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structure which holds the ovum while still within the ovary.

See under vesicle.

Syn. : follicle of de Graaf, ovarian follicle. A closed sac which contains the ovarian ovum. It consists of an external membrane lined with small granular cells (the membrana granulosa) which are condensed at one point to form the discus proligerus. Prior to the ripening of the ovum the v. is situated within the stroma of the ovary, but as maturation advances it becomes superficial, its walls grow vascular, and it is distended with a serous fluid. It finally ruptures, allowing the ovum to escape.