= 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.<Biology 2e by Mary Ann Clark and others>[Section 43.4, ovarian and uterine cycles and their hormonal coordination]{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.
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