1. The Female Reproductive System

2. Female Reproductive Structures

3. Female Reproductive Structures (side view)
Oviduct
Ovary
Uterus
Urinary Bladder
Rectum
Pubic bone
Cervix
Urethra
Body
(erectile tissue)
Vagina
Glans
Clitoris
Vestibular
(Bartholin’s) gland
Prepuce
Labia minora
Labia majora
Vaginal opening

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

5. Reproductive success declines after age 27
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)

8. Ovulation Cells around primary oocyte create a fluid filled cavity
Follicle (primary oocyte)
Cells around primary oocyte create a fluid filled cavity
Follicle pushes outwards
Blood vessels weaken
Secondary oocyte released = ovulation
Growing follicle
Secondary oocyte
Mature follicle
Ovary
Granulosa
cells
Ruptured follicle

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

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 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 is BAD
(ectopic pregnancy)

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

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

18. Ant. Pituitary releases FSH FSH causes maturation of follicle 5
Ant. Pituitary releases FSH
FSH causes maturation of follicle
Follicle releases estrogen
Endometrium builds
Estrogen inhibits FSH, stimulates LH release
Increased LH causes ovulation
Corpus luteum forms
C. luteum secretes progesterone (stops uterine contractions)
Progesterone inhibits LH
No LH  C. luteum disintigrates
Progesterone levels fall (no C. luteum to make it)
Uterus contracts, Endometrium is shed 9 1 7 10 6 2 3 8 11 4 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. Animal Development Umbilical blood vessels Mammalian embryo Chorion
Bird embryo
Amnion
Yolk
sac
Allantois
Fetal blood vessels
Placenta
Maternal blood vessels

21. Human fetal development
10 weeks

22. Placenta
Materials exchange across membranes

23. Human embryonic development
embryo showing tail & limb buds

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

25. 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. 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. 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. Human fetal development
4 weeks
7 weeks

29. 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. Human fetal development
12 weeks
20 weeks

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

32. 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. Human fetal development
30 weeks (7.5 months)
umbilical cord

34. 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. Birth (38-40 weeks) Baby’s head pushes on cervix Oxytocin
Stimulates contraction of uterus
Each contraction causes more oxytocin release
Intestine
Placenta
Umbilical
cord
Wall of
uterus
Bladder
Cervix
Vagina

36. Birth
A positive feedback loop!

37. The end of the journey!