Female Reproduction

Question 1

Describe the germ cell development

Answer 1

• Mitosis of oogonia

- 1st meiotic division to form several million oocytes

Question 2

How many oocytes are present during puberty?

Answer 2

Typically there are about 400-500 ovulations over a lifetime until menopause

Question 3

Where are the receptors located?

Answer 3

Theca interna

Question 4

How is estrogen regulated?

Answer 4

Theca cells produce estrogens which inhibit the secretion of GnRH, LH and FSH

Question 5

What is the difference between inhibin A and inhibin B?

Answer 5

Inhibin A produced by dominant follicle and corpus luteum

Inhibin B produced by small follicles

Question 6

What are the three phases of the follicular wave?

Answer 6

Recruitment: small antral follicles are recruited from the ovarian pool and produce small amounts of E2
Selection: follicles are selected from previously recruited small follicles and either become atretic or develop further.
Dominance: selected follicles that do not become atretic become dominant follicles that produce large quantities of E2

Question 7

Is it common to have more than one follicular wave during the follicular phase?

Answer 7

Yes, more than one follicular wave typically occurs during the follicular phase of the reproductive cycle
minor waves do not result in ovulation

Question 8

What are the levels of FSH and LH during the follicular wave?

Answer 8

Recruitment: high FSH, low LH, no inhibin, no estradiol
Selection: low FSH, moderate LH, low inhibin
Dominance: low FSH, high LH, high inhibin

Question 9

What is atresia?

Answer 9

Degeneration of follicles

Question 10

How is ovulation brought about?

Answer 10

• Elevated blood flow
• Breakdown of connective tissues
• Ovarian contractions

Question 11

What is the effect of a preovulatory LH surge?

Answer 11

• Increase PGF2a: increase contraction and release lysosomal enzymes
• Increase blood flow to ovary and dominant follicle: leads to edema which increases follicular pressure

Question 12

What is the importance of the gap junction breakdown?

Answer 12

Gap junction breakdown between granulosal cells and oocytes will initiate the removal of meiotic inhibition leading to the first polar body initiating haploid oocytes which will lead to fertilization

Question 13

What does the theca interna and granulosa cell form after ovulation?

Answer 13

Corpus luteum

Question 14

What does the tonic centre produce?

Answer 14

Low levels of GnRH to maintain basal levels of LH to stimulate the corpur luteum to secrete P4

Question 15

What is the function of P4?

Answer 15

• Promote alveolar development
• inhibits the myometrium and reduce its contractility and tone (“blocks” pregnancy)
• Negatively feedbacks on GnRH neurons: GnRH, LH, FSH productions are suppressed

Question 16

What happens if fertilization doesnt occur?

Answer 16

If fertilization doesnt occur then the corpus luteum undergoes luteolysis and a new reproductive cycle is initiated

Question 17

What is HcG used for?

Answer 17

hCG stimulates corpus luteum to maintain steroids until feto-placental unit takes over basis of home pregnancy

Question 18

Describe the changes that occur during the menstrual cycle

Answer 18

Ovarian changes: follicle growth and maturation, corpus luteum formed and functioning, luteolysis
Uterine changes: menstruation, proliferative phase, secretory phase, pre-decidual phase
Vaginal changes: high pH watery mucus conducive to sperm survival, low pH viscous mucus inimical to sperm survival

Question 19

Where does fertilization occur?

Answer 19

Fertilization of the ovum occurs in the oviduct
Hydrolytic enzymes in the acrosome loosen the corona radiata cells around the ovum, one sperm penetrates and fertilizes the oocyte
Ciliated cells move the ovum along the oviduct to the uterus

Question 20

Describe the changes in the uterine endometrium during the menstrual cycle

Answer 20

Day 1 - 3: breakdown
Day 3 - 14: estrogenic proliferative phase
Day 14 - 28: progestattional secretory phase

Question 21

How do IUDs work?

Answer 21

IUDs are molded plastic devices which disrupt the normal uterine environment, by slowly releasing snthetic P4

Question 22

How does Plan B work?

Answer 22

Plan B uses synthetic progesterone and should be taken <72 hours after unplanned intercourse or suspected contraceptive failure
high levels of P4 can inhibit ovulation or ovum/sperm transport and implantation to reduce the risk of unplanned pregnancy

Question 23

At what weight are plan B pills less effective and not effective?

Answer 23

• Less effective: 165 - 176lbs (75 -80kh)

- Not effective: >176lbs (>80kg)

Question 24

Explain how RU486 induces abortion

Answer 24

• RU486 is an anti-progesterone
• promote decidual breakdown leading to detachment of the blastocyst
• decrease in secretino of hCG, there will also be a decrease in progesterone in the CL
• there is accumulation of prostaglandins and enhances uterine sensitivity to prostaglandin disturbing the balance between prostaglandin and progesterone increasing uterine contractility
• there will be cervical softening, which faciltates expulsion of the blastocyst

Question 25

When does X silencing occur?

Answer 25

Later in development, about 32 cell stage and it is random (Xp or Xm)

Question 26

Talk about the fetalplacental endocrine unit

Answer 26

- After implantation the blastocyst develops into a trophoblasts, it secretes hCG - hCG maintains steroid production by the corpus luteum and suppresses LH and FSH and restart of the menstrual cycle - at 9 weeks, the placental unit produces pregnenolone that is converted to progesterone - corpus luteus gradually disappears - output of progesterone and estrogens by the fetoplacental unit continuously increases during pregnancy

Question 27

What are some of the changes in the breast during pregnancy?

Answer 27

- changes start two years before end of puberty - estrogens stimulate duct formation and accumulation of fat - estrogen affects the breasts during pregnancy - glucocorticoids, PRL and placental lactogen induce enzymes necessary for milk production - high conc of estrogen and progesterone prevent milk production - after parturition estrogen and progesterone levels fall, but PRL stays high

Question 28

How does the mother's body adapt to pregnancy?

Answer 28

-considered a successful parasite, the fetal placental unit manipulates the maternal host

Question 29

What happens during parturition?

Answer 29

Placenta produces increasing levels of CRH from week 28 to delivery Stimulates SCTH from fetus to increase fetal cortisol and CRH which may have direct effects on PGF and oxytocin actions EStrogen is a stimulant and increase contraction of myometrial layers

Question 30

How long does it take maternal steroid levels to return to normal?

Answer 30

``` 1 - 3 days the pituitary gland will increase in size by about 1/3 during pregnancy and does not decrease until the end of lactation after lactation (>3 months), normal cycles resume in about 17 weeks ```

Question 31

When does menopause typically occur?

Answer 31

age 51 for 90% of women

Question 32

How does menopause start /occur?

Answer 32

Waves of recruitment and atresia starting in utero eventually reduces oocyte pool to about 25,000 then rate of follicular atresia increases

Question 33

Why do people use hormone replacement therapy?

Answer 33

To treat these symptoms including vasometer, osteoporosis, short term memory changes, depression with estrogen

Question 34

What are some examples of hormone replacement therapy?

Answer 34

- progesterone promotes conversion of estradiol to estrone in the target cell, estrone has a lower affinity to estrogen receptors and may dimish cancer risk - long term effects are unknown but bone loss is about 1 -2% per year

Question 35

What are disturbances of the menstrual cycle can occur?

Answer 35

- Primary amenorrhea: genetic defects in gonadal maturation or estrogen synthesis, depletion of follicles - Secondary amenorrhea (failure to ovulate in a six month period): excessive androgen production ,pituitary disease, psychiatric disturbances, nutrition

Question 36

Why does ovulation fail (menstrual cycle without ovulation) sometimes?

Answer 36

- Lack of positive feedback of estrogens - Lack of pulsatility of GnRH release - Lack of ovulation leads to irregular length of period

Question 37

How can you detect ovulation?

Answer 37

- Based on progesterone surge - rise in the basal body temperature in the middle of the cycle - increase of endometrial mucosa secretion - increase in plasma progesterone or excretion of metabolites of progesterone

Question 38

Decribe the process of artificial induction of ovulation

Answer 38

- blocking of estrogen receptors in the hypothalamus, this prevent negative feedback by estrogens and increases LH and FSH - injection of LH, FSH and hCG - injection of GnRH in a pulsatile fashion

Question 39

Describe the process of IVF

Answer 39

- fertilization of ovum and implantation in the uterus after first cleavage is observed - blocks ovarian function creating an artificial corpus luteum - super ovulate ovary to have more than one follicle and induce multiple ovulations - 60% success rate for pregnancy

Question 40

What are the main factors of infertility?

Answer 40

- Age plays a large role, about 20% of NA women have their first child after 35: age dependent loss of follicles - spontaneous abort rates also increase with age

Question 41

What are some other main causes of suboptimal fertility?

Answer 41

- ovulatory defects - pelvic disorders - male factors