Final answer:
High estrogen levels do exert positive feedback on the pituitary, causing an LH surge that triggers ovulation around mid-cycle, typically on day 14 of a 28-day menstrual cycle. The true statement regarding the menstrual cycle is that estrogen levels rise during the luteal phase of the ovarian cycle and the secretory phase of the uterine cycle.
Step-by-step explanation:
Regulation of the Menstrual Cycle
It is true that high estrogen levels briefly exert positive feedback on the brain and anterior pituitary, causing an LH surge around mid-cycle. This LH surge triggers ovulation, which is the release of a mature egg from the ovary. During a typical 28-day menstrual cycle, ovulation usually occurs on day 14, marking the end of the follicular phase and the beginning of the luteal phase. After ovulation, the corpus luteum forms and begins to produce high levels of progesterone, which prepares the endometrium for potential implantation and marks the secretory phase of the uterine cycle.
Considering the four statements about the menstrual cycle, the true statement is option a: "Estrogen levels rise during the luteal phase of the ovarian cycle and the secretory phase of the uterine cycle."