1. The Female Reproductive System Biology 12

2. Female Reproductive Structures

3. Female Reproductive Structures (side view)

4. Step by Step – The life of a female  Ovaries develop in fetus  Produce sex hormones (estrogen and progesterone)  400 000 follicles develop (potential eggs)  Constant decline after puberty  Each menstrual cycle, ~1000 follicles develop but only one becomes mature

5. Do the math! Question: How many periods will a female have in her life?  About 400 Question: How long will she be able to reproduce? (Assuming her first period is at age 13)  33 years, From age 13 – 46 (approximately) Reproductive success declines after age 27

6. Skip to Puberty: Oogenesis  Ovary  Follicles have two kinds of cells  Primary oocyte (  meiosis  becomes the egg)  Granulosa cells (nutrient for the oocyte)  FSH from pituitary causes follicle development  FSH = follicle stimulating hormone Ovary

7. Oogenesis  Nutrient cells around primary oocyte divide  Meiosis I (in the ovary)  Majority of nutrients to one cell (secondary oocyte)  Polar body produced  Meiosis II (occurs later if it contacts a sperm)  Majority of nutrients to one cell again (egg)  Polar body produced

8. Ovulation  Cells around primary oocyte create a fluid filled cavity  Follicle pushes outwards  Blood vessels weaken  Secondary oocyte released = ovulation

9. Ovulation  Surrounding follicle cells become the corpus luteum  Produces progesterone to prepare uterus  No pregnancy?  Corpus luteum dies after 10 days

10. The journey of the oocyte!

11.  Secondary oocyte enters the oviduct  Carried by cilia  Could be fertilized here  If it doesn’t meet a sperm, the oocyte will die within 24- 48 hours  Takes 3-5 days to travel to the uterus  (Progesterone from the corpus lutem stops uterine contractions!)

12. Fertilization (maybe?)  Secondary oocyte and sperm could meet in oviduct (oocyte  egg)  Acrosome on sperm breaks into the egg  Only one sperm can enter

13. Fertilized Egg development (maybe?)  Fertilized egg (zygote) begins to divide

14. Implantation (maybe?)  Fertilized egg can implant in the endometrium (nourishes the egg)  Implantation in the oviduct = BAD (ectopic pregnancy)

15. If fertilization DOESN’T occur (likely!)  Corupus lutem eventually dies  Lack of progesterone causes uterine contracts  Menstruation!  Sheds endometerium  Start all over again… So… how is this cycle controlled?

16. Hypothalamus GnRH Anterior pituitary FSH LH Follicle development Estrogen Secondary female Characteristics Secondary female Characteristics Prepare endometrium Prepare endometrium ovulation Corpus luteum forms (Estrogen and) progesterone Uterine contractions Uterine contractions LH and FSH levels drop -Corpus luteum dies - Progesterone drops - Uterus contracts LH and FSH levels drop -Corpus luteum dies - Progesterone drops - Uterus contracts + LH

17. 2005-2006

18. 1. Ant. Pituitary releases FSH 2. FSH causes maturation of follicle 3. Follicle releases estrogen 4. Endometrium builds 5. Estrogen inhibits FSH, stimulates LH release 6. Increased LH causes ovulation 7. Corpus luteum forms 8. C. luteum secretes progesterone (stops uterine contractions) 9. Progesterone inhibits LH 10. No LH  C. luteum disintigrates 11. Progesterone levels fall (no C. luteum to make it) 12. Uterus contracts, Endometrium is shed 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 11 12

19. What if the egg IS fertilized?  Important to maintain progesterone levels  Stops uterine contractions  HCG (human chorionic gonadotropin) keeps the corpus luteum alive  Corpus luteum keeps progesterone level high  (HCG detected by pregnancy tests)

20. 2005-2006 Animal Development Umbilical blood vessels Chorion Amnion Yolk sac Allantois Fetal blood vessels Maternal blood vessels Bird embryo Mammalian embryo Placenta

21. 2005-2006 Human fetal development 10 weeks

22. 2005-2006 Placenta  Materials exchange across membranes

23. 2004-2005 Human embryonic development  embryo showing tail & limb buds

24. 2004-2005 Human embryonic development  beginning of the eye can be seen, as well the bulging heart & the umbilical cord

25. 2004-2005 Human embryonic development  lens of the eye can be seen forming, the mass of the heart bulging from the chest, & the beginnings of the finger rays

26. 2004-2005 Human embryonic development  beginning of the ear is clearly seen note the bend of the elbow joint has begun, the fingers are forming and toes are beginning to bud off the foot

27. 2004-2005 Human embryonic development  Note the formation of the nose, eyelids, ear flap & well defined toes & fingers 50–60 days (8 weeks) Both knee & elbow are visible. Embryo has formed most of basic organ systems & will spend remainder of development in “fetal” period. Organs grow, mature, & begin to learn their respective functions

28. 2005-2006 Human fetal development 7 weeks4 weeks

29. 2004-2005 Human fetal development  Week 9 - week 40 = fetus  after 12 weeks or so, the baby's development is largely "finished"  some exceptions: brain & lung development Week 16

30. 2005-2006 Human fetal development 12 weeks20 weeks

31. 2005-2006 Human fetal development  The fetus just spends much of the 2 nd & 3 rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week 20

32. 2005-2006 Human fetal development  24 weeks (6 months; 2nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

33. 2005-2006 Human fetal development  30 weeks (7.5 months) umbilical cord

34. 2005-2006 Getting crowded in there!!  32 weeks (8 months) The fetus sleeps 90- 95% of the day & sometimes experiences REM sleep, an indication of dreaming

35. 2005-2006 Birth Hormone induction positive feedback

36. 2005-2006 Intestine Placenta Umbilical cord Wall of uterus Vagina Cervix Birth (36 weeks) Bladder

37. 2005-2006 The end of the journey!