Menstrual cycle

The menstrual cycle coordinates recurring ovarian and uterine changes through hormonal feedback. Cycle day one is conventionally the first day of menstrual bleeding. The ovarian sequence includes follicular development, ovulation and a luteal phase; the uterine lining undergoes shedding, proliferation and secretory changes in response to the changing signals.^[ref]

These are linked sequences, not identical names for one anatomical event. Follicular development concerns the ovary, while endometrial proliferation concerns the uterus. Luteinising hormone, ovarian estrogens and progesterone couple the two. A twenty-eight-day schematic is a teaching example rather than a rule that every cycle has that duration or ovulates on day fourteen. Comparing observations requires specifying the event or phase used to align the records.