What are the phases of the uterine cycle?

• A. Proliferative, secretory, ischemic, and menstrual phases.
• B. Follicular, ovulation, and luteal phases.
• C. Ovulation, menstrual, and ischemic phases.
• D. Proliferative, secretory, and luteal phases.

Answer: (A)

The uterine cycle reflects endometrial changes driven by ovarian hormones, moving through distinct phases as the lining prepares for possible implantation and then sheds if pregnancy doesn’t occur. Estrogen drives the proliferative phase, rebuilding the endometrium after menstruation. After ovulation, progesterone from the corpus luteum leads to the secretory phase, where glands and stroma become well-suited to support a potential embryo. If fertilization doesn’t take place, withdrawal of hormones causes the endometrium to become ischemic and then shed during menstruation. Some descriptions include this ischemic stage as part of the cycle’s turnover, giving four phases: menstrual, proliferative, secretory, and ischemic. This combination captures the full sequence of endometrial changes.

The other options mix in phases from the ovarian cycle (follicular, ovulation, luteal) or omit a key endometrial phase, so they don’t accurately describe the uterine cycle.