1. Pituitary Gland FSH Primordial follicles Growing follicles LH

2. Pituitary Gland FSH Growing follicles Estrogen - inhibin

3. Pituitary Gland Growing follicles Estrogen LH Mature Graafian - +

4. Pituitary Gland Estrogen LH Mature Graafian Corpus luteum ovulation - +

5. Pituitary Gland LH Corpus luteum Estrogen and progesterone -

6. Pituitary Gland Corpus luteum Estrogen and progesterone -

7. Pituitary Gland Corpus luteum Corpus albicans

8. Pituitary Gland LH Corpus luteum Estrogen and progesterone - If implantation occurs

9. Pituitary Gland Corpus luteum Estrogen and progesterone Placenta HCG (human chorionic gonadotropin) If implantation occurs -

10. Uterine Cycle

11. Menstrual Phase Estrogen Proliferative Phase Progesterone + estrogen Secretory Phase Day 1 - 4 Day 5 - 14 Day 15 - 28 Menstrual Cycle

12. Menstrual Phase Estrogen Proliferative Phase Progesterone + estrogen Secretory Phase Decrease in Progesterone + Estrogen Menstrual Phase Day 1 - 4 Day 5 - 14 Day 15 - 28Day 1 - 4 Menstrual Cycle

13. Combined Ovarian and Uterine Cycle

14. FSH is secreted by the pituitary FSH stimulates growth of some of the ovarian follicles The growing follicles produce estrogen and inhibin Estrogen (moderate level) and inhibin inhibits FSH release by the pituitary High Estrogen stimulates increase secretion of LH by the pituitary Estrogen also stimulates growth of the endometrium (proliferative phase) LH stimulates ovulation resulting in the formation of the corpus luteum LH stimulates the corpus luteum to develop, which includes estrogen and progesterone production

15. Estrogen and progesterone inhibit FSH and LH release by the pituitary Estrogen and progesterone stimulates uterine gland secretion of glycogen and continued growth of the endometrium (secretory phase) Decrease in LH inhibits the corpus luteum resulting in a decrease in estrogen and progesterone and deterioration of the corpus luteum, forming the corpus albicans (scar tissue) Decrease in estrogen and progesterone causes vasoconstriction of uterine vessels resulting in menstruation With estrogen and progesterone levels low, FSH can again be released by the pituitary, beginning a new cycle

16. Pituitary Gland FSH Primordial follicles Growing follicles Menstrual Phase Day 1--4

17. Pituitary Gland FSH Growing follicles Estrogen - Proliferative Phase Menstrual Phase Day 1--4Day 5--14 Estrogen

18. Pituitary Gland Growing follicles Estrogen LH Mature Graafian - Day 1--4Day 5--14 Menstrual Phase Proliferative Phase +

19. Pituitary Gland Estrogen LH Mature Graafian Corpus luteum ovulation - + Day 5--14Day 1--4 Menstrual Phase Proliferative Phase

20. Pituitary Gland LH Corpus luteum Estrogen and progesterone - Day 1--4 Menstrual Phase Proliferative Phase Day 5--14 Secretory Phase Estrogen + progesterone Day 15--28

21. Pituitary Gland Corpus luteum Day 1--4 Menstrual Phase Proliferative Phase Day 5--14 Secretory Phase Day 15--28 Decrease in Progesterone + Estrogen Menstrual Phase Day 1--4 Corpus albicans