28 days long. Prepares uterus to receive egg.
Proliferative Phase: First 2 weeks. Uterine lining becomes engorged with blood. After 14 days release of an egg takes place in reponse to LH
Secretory Phase: Stage immediately surrounding ovulation.
Ischemic Phase: If fertilization does not occur estrogen and progesterone levels fall. Vascular changes cause endometrium to become pale and small blood vessels rupture.
Menstrual Phase: Sloughing of inner lining of uterus occurs. Usual blood loss of 50 mL.