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( Ovulation)
Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. Ovulation also occurs in the estrous cycle of other animals, which differs in many fundamental ways from the menstrual cycle. The process of ovulation is controlled by the hypothalamus of the brain and through the release of hormones secreted in the anterior lobe of the pituitary gland, (Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH)). In the follicular (pre-ovulatory) phase of the menstrual cycle, the ovarian follicle will undergo a series of transformations called cumulus expansion, this is stimulated by the secretion of FSH. After this is done, a hole called the stigma will form in the follicle, and the ovum will leave the follicle through this hole. Ovulation is triggered by a spike in the amount of FSH and LH released from the pituitary gland. During the luteal (post-ovulatory) phase, the ovum will travel through the fallopian tubes toward the uterus. If fertilized by a sperm, it may perform implantation there 6-12 days later. In humans, the few days near ovulation constitute the fertile phase. The average time of ovulation is the fourteenth day of an average length (twenty-eight day) menstrual cycle. It is normal for the day of ovulation to vary from the average, with ovulation anywhere between the tenth and nineteenth day being common. Cycle length alone is not a reliable indicator of the day of ovulation. While in general an earlier ovulation will result in a shorter menstrual cycle, and vice versa, the luteal (post-ovulatory) phase of the menstrual cycle may vary by up to a week between women.
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