Small sacs in the ovaries in which the egg matures and from which it is discharged at the time of ovulation. When the mature, an egg is discharged and the corpus luteum develops in the place from which the egg was released. Named after Graaf, a seventeenth century Dutch anatomist.
Of the egg-producing structures in the ovaries, the one that produces the lead egg (ovum) ready for fertilization.
Fully developed, egg-containing sac in the ovary that ruptures during ovulation to release an egg, or ovum. Many primary follicles, each containing an immature ovum, are embedded in the wall of the ovary. Under the influence of follicle-stimulating hormone released by the pituitary, one follicle ripens into a mature graafian follicle containing a mature ovum in the early phase of each menstrual cycle. At ovulation the follicle ruptures and the ovum is released. The collapsed follicle—now the corpus luteum— produces the hormone progesterone and prepares the uterus to receive a fertilized egg; if fertilization does not occur, the corpus luteum is shed in menstruation.
A mature follicle in the ovary prior to ovulation, containing a large fluid-filled cavity that distends the surface of the ovary. The oocyte develops inside the follicle, attached to one side.
A mature vesicular follicle of the ovary. Beginning with puberty and continuing until the menopause, except during pregnancy, a graafian follicle develops at approx, monthly intervals. Each follicle contains a nearly mature ovum (an oocyte) that, on rupture of the follicle, is discharged from the ovary, a process called ovulation. Ovulation usually occurs 12 to 16 days before the first day of the next menstrual period. Within the ruptured graafian follicle, the corpus luteum develops. Both the follicle and the corpus luteum are endocrine glands, the former secreting estrogens, and the latter, estrogen and progesterone.