Final answer:
The ovulatory phase is characterized by a surge in the luteinizing hormone (LH), which triggers the maturation and release of the egg during ovulation around day 14 of a typical 28-day menstrual cycle.
Step-by-step explanation:
The ovulatory phase is characterized by a surge in luteinizing hormone (LH). This LH surge is critical for the ovulation process, as it stimulates the maturation of the egg and leads to the weakening of the follicle wall, allowing the egg to be released.
The surge in LH is preceded by a continuous rise in estrogen levels, which initially suppresses LH. However, as estrogen reaches a high concentration, it switches from negative to positive feedback, prompting the pituitary gland to release a significant amount of LH that triggers ovulation.
In a 28-day menstrual cycle, this typically occurs around day 14, marking the transition from the follicular phase to the luteal phase of the ovarian cycle.