1. Reproduction (2)

2. Female Reproductive System
Consists of:
Ovaries: produce egg each month, & produce sex hormones.
Oviducts (fallopian tubes): conduct egg & it’s the location of fertilization.
Uterus (womb): houses developing embryo and fetus.
Vagina: receives penis during copulation and serves as birth canal.

3. Female Reproductive System
Mitosis of primordial oogonia occurs in female fetus until midgestation (peak of 7 million oocytes) and then ceases.
There it a progressive loss of oocytes & by puberty there are approximately 400,000 oocytes (only ~400 follicle ovulate in women ).
If a woman starts her menstrual cycle at the age of 11she will have 400 cycle before she goes into menopause.

4. Female Reproductive System
The follicles have two kind of cells:
Thecal cells  similar to Leydig cells  they have LH receptors stimulated to produce testosterone & estrogen.
Granulosa cells  similar to Sartoli cells in male  they have FSH receptors will take testosterone from thecal cells & convert it into estrogen + it produce inhibin.
These two cells work together to produce sex steroid hormones (estrogen, progesterone and testosterone)
Remember! Testosterone in a precursor for estrogen, so if you don’t have testosterone you won't have estrogen.
Changes in the ovaries are the result of changing levels of FSH & LH from the anterior pituitary
At menopause: oogenesis ceases

5. Female Reproductive System
Primary follicle + secondary follicle + Graafian follicle stages involve the hormone FSH (they are FSH dependent), and it is known as the follicular phase.
For ovulation to occur we need the hormone LH (LH dependent).
The luteal phase is LH dependent, it’s when we have the formation of the corpus luteum (yellow body) .
The corpus luteum has granulosa and thecal cells which are stimulated by LH to produce estrogen, progestron, inhibin and testosterone.
If fertilization did not occur  corpus luteum will degenerate & will be known as the corpus albican (white body).

6. Maturation of The Oocyte
Oocyte begins first meiotic division in the utero, the first division is arrested in prophase until the time of ovulation.
After ovulation  we’ll have the completion of the first meiotic division  the results are a secondary oocyte + the first polar body
Sperm cell penetration (fertilization) initiate the completion of the second meiotic division  secondary oocyte and a second polar body.

7. Maturation of The Oocyte
Before birth:
Mitosis of the oogonia then the beginning of the first meiotic division  it is stopped at prophase we’ll have the formation of the primary oocyte.
In adolescence:
When a girl starts menstrual cycle  the completion of the first meiotic division during ovulation  we’ll have secondary oocyte and first polar body
No fertilization  secondary oocyte dies
There is fertilization  completeion of the second meiotic division + apperence of the second polar body

8. Control of Ovarian Steroidogenesis
Hypothalamus produces GnRH.
GnRH stimulates the pituitary to produce LH & FSH.
LH & FSH will act on the ovary and will stimulate the granulosa and thecal cell to produce estrogen, progesterone & inhibin
Inhibin will inhibit the secretion of FSH
Progesterone will inhibit FSH & GnRH
Estrogen will inhibit LH & GnRH

9. Important!
Estrogen can inhibit or STIMULATE LH & GnRH

10. Menstrual Cycle Devided into:
Overia cycle (changes that are happening in the ovaries) :
Follicular phase
Ovulation
Luteal phase
Endometrial cycle (changes that are happening in the lining of the uterus, or endometrium):
Proliferative phase
Secretory phase
menstruation

11. Ovarian Cycle : Follicular Phase
Two hormones are secreted, FSH & LH.
FSH is higher than LH.
High levels of FSH will stimulate approximately 10 follicles.
Of these 10 follicles only 1 will mature.
Upon the FSH & LH stimulation the cells which are surrounding the ove (granulosa + thecal cells) will produce estrogen
Estrogen will be high and will inhibit FSH & LH.

12. Ovarian Cycle : Follicular Phase
Estrogen will keep increasing until it peaks
When it peaks it won’t inhibit FSH & LH anymore
Estrogen will actually STIMULATE FSH & LH
So we will have the peak of LH, it is known as LH surge
We will have the peak of FSH, it is known as FSH surge

13. Ovarian Cycle : Follicular Phase
High levels of LH will stimulate ovulation
If we didn’t have the LH surge ovulation wouldn’t have occur

14. Ovarian Cycle: Ovulation
What is the sequence for ovulation to occur?
We need a peak in estrogen
Then we need a peak in LH
Then we can get ovulation
It usually happens one day for each one.

15. Ovarian Cycle: Luteal Phase
After ovulation and the ova has been released the cells that are remaining behind (granulosa and thecal cells) they will become as the luteal cells.
The luteal cells will be stimulated by LH.
They will continue to produce estrogen and will start to produce progesterone.
That’s why in the luteal phase we’ll have high levels of estrogen, progesterone and inhinin.

16. Ovarian Cycle: Luteal Phase
That’s why in the luteal phase we’ll have high levels of estrogen, progesterone and inhibin.
These three hormone negatively feeding back the hypothalamus
There will be less GnRH, less LH, and less FSH
Because levels of LH & FSH are falling the corpus luteum will degenerate because it is not able to produce any more hormones

17. Ovarian Cycle: Luteal Phase
It will be known as corpus albican
Because the corpus luteum became corpus albican  it is not producing anymore progesterone or estrogen level of those two will decrease  the inhibition will decrease the pituitary & hypothalamic hormones will be secreted  so the cycle will continue.

18. Uterine or Endometrial Cycle
Proliferative Phase
Due to high levels of estrogen in the follicular phase, estrogen will act on the endometrium and will cause it to proliferate (divide), it is known as the proliferative phase.

19. Uterine or Endometrial Cycle
Secretory Phase
Due to high levels of progesterone will make the endometrium an endometruim that has nutrients secreted into it.
We need nutrients secreted into the endometrium to provide nutrients for the embryo if fertilization occur.

20. Uterine or Endometrial Cycle
Menstration
If fertilization did not occur the levels of estrogen and progesterone will decrease  they’re not supporting the endomerium anymore  the cells of endometrium begin to die  2/3 of the layer of the endometrium will be shed, and that’s why we have menstruation.

21. Functions of Estrogen & Progesterone
Estrogen is responsible for the development and maintenance of the secondary sexual characteristics.
Less body and facial hair, more fat beneath the skin to give a rounded appearance
Enlargement of pelvic girdle and cavity to give wider hip
Both estrogen & progesterone
Are required for breast development
Help maintain endometrium
Help suppress gonadotropin secretions
Inhibit prolactin secretion

22. Although we have high levels of estrogen and progesterone they are inhibiting the actual secretion of milk.

23. Fertilization, Pregnancy & Parturition
During fertilization we have approximately 300 million sperm ejaculated into the vagina.
Only ~ will survive & enter the fallopian tube & stay for 3 days.
The ova remain viable for ~ 24 hours.
The fertilization has to occur during the time of ovulation because the ova remain viable for only 1 day

24. Fertilization, Pregnancy & Parturition
When does fertilization occur?
It occur if intercourse takes place within 3 days prior to the day of ovulation.

25. Fertilization, Pregnancy & Parturition
During fertilization from the ~200 sperm only one sperm will reach the ova and will bind to receptors on it.
Once it binds to the receptor it will start secreting enzymes which are on the acrosome
This will allow it to penetrate the ova wall ( the jelly coat of the oocyte)

26. Fertilization, Pregnancy & Parturition
Once it penetrates, the ova secrets granules into the layer which is surrounding it.
By secreting these granules it prevents further sperms from entering  only one sperm enters the ova.
only the head will enters the ova, the tail will remain outside

27. Fertilization, Pregnancy & Parturition
We will have the fusion of the two nuclei, and the formation of the zygote.
Here the second meiotic division is completed, and the second polar body is formed.
The other sperms of the ~200 are needed, because when the ova is secreted it is surrounded by a layer of cells, so these sperms get rid of these cells.

28. Fertilization, Pregnancy & Parturition
Fertilization takes place in the fallopian tube.
After fertilization we have the zygote
The zygote begins the cleavage
While it’s undergoing the cleavage, it is passing down into the fallopian tube

29. Fertilization, Pregnancy & Parturition
After approximately 5 days we will have the formation of the Morula
Then we will have the formation of the blastocyst
Blastosyst has an inner cell mass which will form the embryo, and the surround layer of trophoblast cells which will form fetal part of the placenta

30. Fertilization, Pregnancy & Parturition
By approximately 7 days this blastocysts will implant into the endometrium.
During implantation will start breathing from the secretory endometrium.
When we have the implantation we will have the formation of the hormone human corionic gonadotropin (hormone of pregnancy hCG)

31. Fertilization, Pregnancy & Parturition
hCG is needed because it is the hormone that will stimulate the corpus luteum to produce estrogen & progesterone during the first 7 weeks of pregnancy
It stimulates the corpus luteum because it has a similar structure to LH

32. Implantation & Formation of Placenta
hCG peaks around 8 weeks of pregnancy, then it will decrease again
Because we have high levels of hCG, the levels of estrogen and progesterone will increase ( they are initially secreted by the corpus luteum).
By 10 weeks, and after the placenta forms the corpus luteum production of estrogen and progesterone is not enough  the placenta takes over and will start producing them.

33. The Structure & Function of The Placenta
The umbilical cord has the umbilical vain and two umbilical arteries.
The umbilical vain will take oxygenated blood from the mother to the fetus
The umbilical arteries will take de-oxygenated blood from the fetus to the mother
The fetal circulation DOES NOT join the mother circulation

34. The Structure & Function of The Placenta
The placenta is a unique organ where exchange between fetal blood & mother’s blood take place.
The umbilical arteries will take de-oxygenated blood to the fetal part of the placenta  to the chorionic villi.
Chorionic villi are treelike extensions of the chorion; they project into maternal tissue
Chorionic villi are similar to capillaries, the have very thin wall that allow exchange of gases, nutrients and waste

35. Functions of Placenta 1- Exchange molecules across placenta:
The umbilical arteries deliver fetal blood  chorionic villi  blood circulates within villi  umbilical veins  back to the fetus
Maternal blood is delivered to and from the cavities within decidua basalis ( maternal part; located between chorionic villi)  maternal and fetal blood are brought close together.

36. Functions of Placenta 2- Endocrine functions of placenta:
Human chorionic gonadotropin (hCG):
Similar to LH: maintains mother’s corpus luteum for the first few weeks.
Human placental lactogen (hPL):
Has actions similar to GH and prolactin
Synergizes with GH from the mother producing diabetic-like effecs in the pregnant woman  polyuria, dehydration & thirst.
Lipolysis increases free fatty acids
Decreased maternal utilization of glucose  increse blood glucose concentration that is made available for the fetus

37. Labour & Parturition
The hormone needed for parturition & milk ejection is oxytocin
The hormone needed for milk production is prolactin

38.  Good Luck 