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Female Reproductive Cycle

Female Reproductive Cycle. Review: Female hormones Ovarian Cycle Menstrual Cycle Fertilization. Ovary - Functions. Gametogenesis Ovulation Hormone production Estrogen Progesterone. Estrogen. Involved in the control of pituitary release of FSH & LH

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Female Reproductive Cycle

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  1. Female Reproductive Cycle Review: • Female hormones • Ovarian Cycle • Menstrual Cycle • Fertilization

  2. Ovary - Functions • Gametogenesis • Ovulation • Hormone production • Estrogen • Progesterone

  3. Estrogen • Involved in the control of pituitary release of FSH & LH • Promotes growth of the uterus and controls its function • Increases mobility of joints • spinal segments and pelvis • Reduces sodium excretion • Increases water retention and conservation

  4. Progesterone • Promotes breast development • Increases fat storage • Decreases smooth muscle tone (~>constipation) • Decreases vascular tone (~>varicose veins) • Increases pulmonary ventilation • Increases temperature

  5. Pituitary Gland • Anterior Pituitary produces: • FSH • LH • Prolactin • Posterior Pituitary produces: • Oxytocin

  6. FSH Follicle stimulating hormone • Produced by the anterior pituitary • Stimulates the ovarian follicles to mature

  7. LH Lutenizing ormone • Produced by the anterior pituitary • Helps in the maturation of the ovarian follicles • Stimulates the development of the Corpus Luteum and its production of progesterone • this is the granulosa cells of the follicle after ovulation • “Surge” causes expulsion of the mature ova

  8. Prolactin • Produced by the anterior pituitary • Stimulates the breast to produce fluids (milk)

  9. Oxytocin • Produced by the posterior pituitary • Stimulates contraction of tissues • Uterus: to push the baby out • Vascular: to shut off the large blood supply at the placental attachment • Breast: stimulates contraction of the myoepithelial cells around the lactiferous ducts to push fluids out of the breast • Stimulates more prolactin production

  10. Hypothalamus • Produces GnRH • GnRH is produced in response to high levels of estrogen • Stimulates the anterior pituitary to produce its hormones (surge of FSH & LH… ovulation)

  11. Human Chorionic Gonadotrophin • HCG is produced by the chorionic membrane or its earlier embryonic or primitive tissue • Hormone of pregnancy • Acts like LH… • controls the Corpus Luteum of Pregnancy to maintain its production of progesterone • Inhibits the pituitary in its production of LH

  12. Relaxin • Produced by the Corpus Luteum of Pregnancy • Softens the cervix • Inhibits uterine motility

  13. Ovarian Cycle

  14. Ovarian Cycle • Starts at the beginning of a menstrual flow when the estrogen is at its lowest • Low estrogen stimulates the anterior pituitary to produce FSH & LH • FSH & LH cause the ovaries to • begin maturing a number of follicles and • produce estrogen and progesterone

  15. Ovarian Cycle • As estrogen and progesterone rise, the anterior pituitary shuts off the production of FSH & LH • This causes all but one of the follicles to regress (selection) • usually the larger or most mature

  16. Ovarian Cycle • Estrogen continues to be produced as the follicle matures • Eventually estrogen levels are high enough to stimulate the hypothalamus to produce GnRH

  17. Ovarian Cycle • GnRH in turn, stimulates the anterior pituitary to secrete a sudden surge of FSH & LH • This causes the ovary to extrude the ova from the follicle… OVULATION

  18. Ovulation takes place 12–14 days after the onset of the cycle Remember… the onset was the first day of menses • Ovulation will take place 5–7 days after the end of menses

  19. Ovarian Cycle • The ova is only available for fertilization for a short period of time • NOTE: • Some references indicate that the ova may be available for fertilization for up to 3 days • More recent thinking is that it is only hours and the sperm need to be available at the time of ovulation • Sperm can live 2–7 days

  20. Ovarian Cycle In the normal cycle… • No fertilization takes place • Estrogen and progesterone levels begin to decline (day 22–24)

  21. Ovarian Cycle • Estrogen is once again at its lowest level (about day 28) • Cycle repeats… menses begins • body recognizes it is not pregnant • does not need the prepared endometrial lining

  22. Meanwhile… • The uterus during this time has • increased its blood vascular supply • thickened its inner wall (endometrium) • prepared to receive the fertilized ova and nurture it into a fetus • Remember, estrogen levels have been high, promoting the growth of the uterus

  23. Menstrual Cycle

  24. Menstrual Cycle • The endometrium undergoes a three-phase cycle of its own: • Phase I – Proliferative • Phase II – Secretory • Phase III – Regression

  25. Phase I – Proliferative • As the ovulatory cycle progresses, the endometrium increases its tissue growth • begins about the 7th day (end of menses) and continues for about another 14 days (about day 21) • The glands and blood vessels of the endometrium do not secrete nutrients as yet

  26. Phase II – Secretory • Day 21, the glands of the endometrium have become dilated and tortuous and have begun to secrete nutrients for the fertilized ova • As it waits for the fertilized ova to embed itself • Blood vessels have become coiled • Endometrial growth stops • Hormones begin to decline • The ova may embed itself in the endometrium but if not, the body will wait before regressing into Phase III

  27. Phase III – Regression • If fertilization HAS NOT taken place, the estrogen and progesterone levels begin to decline (day 21) • The lack of fertilization and the declining hormone levels triggers a release of the endometrial lining

  28. If Fertilization Occurs…

  29. Fertilization • Day 12-14 ovulation occurs • The oocyte travels down the fallopian tube toward the uterus and is fertilized by waiting sperm • The oocyte begins to develop and multiply in cell number • forms a primitive membrane called the chorion • This chorionic membrane begins to produce Human Chorionic Gonadotrophin (HCG)… the pregnancy hormone

  30. HCG is a luteinizing hormone • Acts like LH on the corpus luteum • now called the Corpus Luteum of Pregnancy • Maintain the levels of estrogen and progesterone necessary to sustain the endometrial lining for implantation of the fertilized ova (zygote)

  31. Entire event (ovulation-implantation) takes place over about 14 days • Starts at ovulation (day 14) • Takes about 5 to 7 days to get to the uterus • Then 5 to 7 more days to embed itself in the endometrium

  32. This brings us to about day 28 when normally menses takes place but this time… • hormone levels are high enough to maintain the endometrium and menstruation does not occur (HCG is stimulating estrogen and progesterone)

  33. Please Note • Some women experience “spotting” when implantation occurs (~day 28) • This can often be mistaken for a light cycle • She may not realize that she is pregnant • May result in inaccurate EDD

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