The Reproductive System of the Female

1. The Reproductive System of the Female Chapter 19

6. The Ovarian Cycle Oogenesis occurs within ovarian follicles Primordial follicle Clusters of primary oocytes surrounded by follicles At puberty a different group is activated each month Ovarian cycle Involves: Formation of primary follicles Formation of secondary follicles Formation of tertiary follicles Ovulation Formation and degeneration of corpus luteum

11. The Uterine Cycle Consists of 3 stages: Menses Proliferative phase Secretory phase

12. The Uterine Cycle: Menses Begins menstrual cycle Degeneration of functional zone of endometrium Triggered by decline in progesterone and estrogen Due to disintegration of corpus luteum Endometrial arteries constrict Reduce blood flow Necrosis of secretory cells, epithelial cells, other tissue (due to lack of oxygen and nutrients) Tissue sloughed off until zone is gone Weakened arteriole walls collapse, releasing blood Blood and tissue pass through vagina to orifice

13. Uterine Cycle: Proliferative Phase Begins after completion of menses Surviving epithelial cells multiply Spread across surface of endometrium Stimulated by rising estrogen Due to growth of another set of ovarian follicles By ovulation, endometrium several mm thick New set of uterine glands secreting watery mucus Functional zone with small arteries

14. Uterine Cycle: Secretory Phase Uterine glands enlarge Increase rate of secretion B/c endometrium prepares for arrival of developing embryo Stimulated by progestins and estrogens from corpus luteum Begins at time of ovulation Persists as long as corpus luteum intact Secretory activities peak about 12 days after ovulation 1-2 days later glandular activity declines; uterine cycle over New cycle begins with menses

17. Hormones and Follicular Phase FSH Stimulates follicular development Primordial follicles ? primary follicles Estrogen Released as follicular cells multiply Functions: Stimulating bone and muscle growth Establishing and maintaining secondary sex characteristics Affects CNS Particularly hypothalamus (? sexual drive) Maintains functional accessory reprod glands and organs Initiates repair and growth of endometrium

18. Hormones and the Follicular Phase Early follicular phase Estrogen and inhibin levels are low Have complementary effects on secretion of FSH and LH ? estrogen inhibit LH secretion Follicular development ? estrogen and inhibin Secondary follicle development Estrogen continues to increase FSH levels ? due to inhibin (negative feedback)

19. Hormones and the Follicular Phase Tertiary follicle development Dramatic ? in estrogen (in preparation for ovulation Acts on hypothalamus and stimulates production of GnRH Leads to secretion of FSH and LH Day 14 estrogen levels peak High estrogen levels triggers surge of LH LH triggers rupture of follicular wall and ovulation

21. Hormones and the Luteal Phase ? LH levels trigger: Ovulation Remaining follicle cells to form corpus luteum Manufacture progesterone Principle hormone of this phase Prepares uterus for pregnancy: Stimulates growth and development of blood supply and secretory glands of endometrium Stimulates metabolic activity and elevates basal body temp Levels remain high for one week Levels high for 2 days If no pregnancy: corpus luteum nonfunctional Remarkable ? in estrogen, progesterone, and inhibin Stimulates hypothalamus and GnRH ? Increase in production of FSH and LH (cycle begins again)