You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Ovulation occurs because of surge of - and explain in detail?
Ans. is 'a' i.e., LH * Ovulation occurs because of luteinizing hormone (LH) surgeHormonal regulation of the menstrual cycle* Menstrual cycle involves the interplay of ovarian, pituitary and hypothalamic hormones.* At the beginning of the cycle, the estrogen level is very low and progesterone level is negligible.* Therefore, the pituitary and hypothalamus are free from the negative feedback effect of estrogen and progesterone.* Hence the hypothalamus secretes GnRH and the anterior pituitary secretes FSH and some LH.* FSH stimulates follicular development.* Ovarian follicles secrete estrogen.* Estrogen tends to suppress FSH secretion, but progressive follicular development ensures a rise in estrogen level.* Around day 11 of the cycle, the estrogen level crosses a certain threshold.* Above this threshold level, estrogen has a positive feedback effect on LH secretion, and to some extent also on FSH secretion.* This leads to LH and FSH surge.* The LH surge is essential for ovulation.* After ovulation has taken place on day 14, the corpus luteum starts developing under the influence of LH.* Corpus luteum secretes estrogen, progesterone and inhibin.* The combined effect of these hormones is to suppress the secretion of FSH and LH by negative feedback effect on the anterior pituitary, and to a lesser extent also on the hypothalamic GnRH secretion.* Absence of support from FSH and LH leads to regression of the corpus luteum.* Regression of the corpus luteum leads to a sharp decline in estrogen and progesterone levels.* Withdrawal of support from estrogen and progesterone leads to menstrual bleeding.* Thus one cycle ends and the next cycle begins.