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REPRODUCTIVE CHARACTER DISPLACEMENT AND SPECIATION IN PERIODICAL CICADAS, WITH DESCRIPTION OF A NEW SPECIES, 13-YEAR

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This development of egg cells occurs within the ovary once a month. One mature egg cell is released from one of the ovaries. The ovaries con- tain follicles. A follicle is a hollow bundle of cells with an egg inside. The follicle helps the egg mature. As the egg matures, the follicle enlarges and fills with fluid. The greatly enlarged follicle moves to the edge of the ovary and bursts, releasing the egg and the fluid. This event is ovulation, the release of an egg from the ovary. (See Figure 17-4.) The egg cell gets swept into the oviduct (or fallopian tube), a long tubular structure found next.