Final answer:
The luteal phase of the ovarian cycle typically lasts about 14 days, during which the corpus luteum produces hormones to prepare the uterus for a potential pregnancy. If fertilization does not occur, the decline in progesterone levels marks the end of this phase and the start of menstruation.
Step-by-step explanation:
The luteal phase is the third and final phase of the ovarian cycle, occurring after ovulation. In a typical 28-day menstrual cycle, the luteal phase spans approximately 14 days, starting around day 15 and ending around day 28. During this phase, the ruptured follicle transforms into the corpus luteum, which secretes essential hormones, including progesterone and estrogen. Progesterone plays a crucial role by stimulating the buildup of the endometrium in preparation for a potential pregnancy and suppressing further ovulation by inhibiting the production of FSH and LH. If the egg is not fertilized, the corpus luteum degenerates towards the end of the luteal phase, leading to a decrease in progesterone levels and the eventual start of menstruation, thus concluding the cycle.