12: Menstrual Cycle And Ovulation

Question 1

Where are the two meiotic arrests in oocytes and when they occur?

Answer 1

1st: at prophase 1, during fetal life
2nd: at metaphase II: LH surge, dont progress until fertilization

Question 2

What is elevated in first and second meiotic arrests?

Answer 2

First: cAMP
Second: MAPK

Question 3

When are polar bodies 1 and 2 extruded?

Answer 3

Polar body 1: at LH surge/ovulation

Polar body 2: at fertilization

Question 4

Ovarian reserve

Answer 4

About 300,000 primordial follicles

Question 5

How many follicles will actually develop and ovulate?

Answer 5

400-500

Question 6

What induces formation of primary follicles from primordial follicles

Answer 6

FSH

Question 7

What induces vascularization in secondary follicle formation?

Answer 7

Angiotensin

Question 8

Histo of theca interna

Answer 8

Looks like it has adipose (clear splotches) bc it forms steroid hormones

Question 9

What causes increased follicle size once antrum is formed?

Answer 9

Increase of antral size/volume of fluid + proliferation of granulosa cells

Question 10

What do theca interna and granulosa cells respond to during antral phase of follicle?

Answer 10

Theca interna: responds to LH

Granulosa: FSH

Question 11

What do theca interna and granulosa synthesize during antral phase of follicle?

Answer 11

Theca interna: androgens

Granulosa: converts thecal cell’s androgens into estrogens

Question 12

What is induced in granulosa cells in late follicular phase?

Answer 12

LH receptors

Question 13

When does the oocyte itself grow the most?

Answer 13

Early follicle stages

Question 14

What hormone sensitivity aids in selection of follicles to continue developing

Answer 14

FSH

Question 15

How is the dominant follicle chosen in each cycle?

Answer 15

FSH declines, and the largest follicle with the most FSH receptors will become dominant

Question 16

Follicular atresia

Answer 16

Primary and antral follicles that did not become the dominant follicle -> apoptosis

Question 17

Theca cells in follicular atresia

Answer 17

Persist and repopulate the stroma of the ovary + retain LH receptors so they can still produce androgens

Question 18

Hallmark of follicular atresia histo

Answer 18

Glassy membrane due to thick, folded basemement membrane material

Question 19

HPO Axis reflex

Answer 19

Hypothalamus secretes GnRH -> binds anterior pituitary to secrete FSH and LH -> bind ovaries to produce estrogen, progestin, inhibin, activin

Question 20

GnRH in a pulsatile rhythm

Answer 20

Causes pulsatile release of LH

Question 21

Anterior pituitary sensitivity in early follicular phase vs later follicular phase

Answer 21

Early: not very GnRH sensitivite -> only elicit small amounts of LH
Later: become more sensitive -> larger releases of LH

Question 22

What does LH act on in the follicular phase vs luteal phase

Answer 22

Follicular phase: theca cells

Luteal phase: CL

Question 23

What determines whether cells respond to activins or inhibins

Answer 23

Where follicles are in different parts of the ovarian cycle

Question 24

What three hormones cause the LH surge

Answer 24

Estrogen, progestin, activins

Question 25

Why do LH and FSH rapidly decrease at the start of the luteal phase?

Answer 25

Negative feedback from estradiol, progestin, inhibin

Question 26

When is basal body temp higher and lower

Answer 26

Follicular phase: high estrogen -> lower BBT | After ovulation: high progesterone -> raises BBT

Question 27

What happens to basal body temp with regression of CL

Answer 27

Drop in BBT that roughly coincides with onset of next menstruation

Question 28

What hormone causes higher body temp?

Answer 28

Progesterone

Question 29

When does estrogen begin to rise in follicular phase?

Answer 29

About 1 week prior to ovulation

Question 30

Where does the bulk of progesterones come from in the body?

Answer 30

Peripheral conversion from pregnenolone

Question 31

When is menopause officially started?

Answer 31

12 months after last menstrual period

Question 32

Hormonal changes that cause menopause

Answer 32

Reduction in estrogen and inhibin -> no negative feedback on LH and FSH -> high LH and FSH

Question 33

Perimenopause presentation

Answer 33

irregular periods, vaginal and skin dryness, hot flashes, night sweats, sleep disturbances, mood changes, weight gain and slow metabolism, thinning hair, loss of breast fullness

Question 34

Treatment for menopause symptoms

Answer 34

Mostly to manage S/S and prevent/manage chronic conditions that occur with aging: estrogen therapy, vaginal estrogen, low-dose antidepressants, gabapentin (for hot flashes)