Write phases of endometrial cycle.
Phases of the Endometrial Cycle
The endometrial cycle (also called the uterine cycle) is the monthly series of changes in the lining of the uterus (endometrium) in response to hormonal fluctuations during the menstrual cycle. It typically lasts 28 days (though it can vary from 21–35 days in healthy individuals). The cycle prepares the uterus for potential pregnancy. Below are the three main phases, based on established medical data from sources like the American College of Obstetricians and Gynecologists (ACOG).
Menstrual Phase (Days 1–5)
The endometrium sheds, causing bleeding (menstruation).
Thickness: Reduces from ~8–13 mm to ~1–4 mm.
Hormones: Low estrogen and progesterone levels trigger this.
Duration: Averages 3–7 days; blood loss is typically 30–80 mL.
Proliferative Phase (Days 6–14)
The endometrium rebuilds and thickens under estrogen stimulation from growing ovarian follicles.
Thickness: Grows to ~5–7 mm by ovulation.
Key event: Cells proliferate, forming a new functional layer.
Ends with ovulation around day 14.
Secretory Phase (Days 15–28)
The endometrium becomes glandular and nutrient-rich, preparing for embryo implantation, driven by progesterone from the corpus luteum.
Thickness: Peaks at ~7–16 mm.
If no pregnancy occurs, hormone levels drop, leading back to menstruation.
Key event: Spiral arteries develop for potential placental support.