Ovulation occurs: September 2005

Ans. B: 14 days prior to next menstruation 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, LH and 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 (postovulatory) phase, the ovum will travel through the fallopian tube toward the uterus. If feilized by a sperm, it may perform implantation there 6-12 days later. In humans, the few days near ovulation constitute the feile phase. The average time of ovulation is the foueenth 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, but commonly occurs 14 days before the next cycle. Cycle length alone is not a reliable indicator of the day of ovulation.