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graafian follicle
(grah´fe-әn)
a small sac, embedded in the ovary, that encloses an oocyte. At puberty each ovary has a large number of immature follicles (primordial follicles), each of which contains an undeveloped egg cell. About every 28 days between puberty and menopause, one of the follicles
ripens, growing in size and maturing into a graafian follicle. The oocyte inside it becomes larger, the follicular wall thickens,
and fluid collects around the growing oocyte. The follicle moves to the surface of the ovary, forms a projection, and finally
breaks open to release the oocyte, which then passes down the fallopian tube to the uterus. (See ovulation.) Called also vesicular ovarian follicle.
Copyright 2007. An Elsevier publication. All rights reserved.
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