Menstrual Cycle and Ovulation

Question 1

the menstrual cycle can be broken down into 2 different cycles. What are they?

Answer 1

ovarian cycle and the endometrial cycle

Question 2

what are the phases of the ovarian cycles?

Answer 2

follicular phase and the luteal phase

Question 3

what are the phases of the endometrial phase?

Answer 3

menses, proliferative phase, and secretory phase

Question 4

what is the primary hormone involved in the follicular phase?

Answer 4

estrogen

Question 5

what is the primary hormone involved in the luteal phase?

Answer 5

progesterone

Question 6

what stage of meiosis are the primordial germ cells in arrest at?

Answer 6

prophase I

Question 7

what keeps the primordial germ cells in meiotic arrest?

Answer 7

elevated levels of cAMP

Question 8

how long do the primordial germ cells stay in meiotic arrest in prophase I?

Answer 8

until the LH surge

Question 9

where does the second meiotic arrest occur?

Answer 9

metaphase II

Question 10

how does the second meiotic arrest in metaphase II occur?

Answer 10

elevated levels of MAPK proteins

Question 11

when is there resumption of meiosis II?

Answer 11

only at fertilization

Question 12

what is the functional unit of the ovary?

Answer 12

ovarian follicle

Question 13

what happens in the follicle of the ovary?

Answer 13

gametes develop and mature

Question 14

what is the primordial follicle surrounded by?

Answer 14

a single layer of pregranulosa cells

Question 15

what does the primordial follicle represent?

Answer 15

the ovarian reserve

Question 16

within the primordial follicle what type of oocyte would you find?

Answer 16

primary oocyte

Question 17

what is the primary follicle surrounded by?

Answer 17

a single layer of granulosa cells- cuboidal shape

Question 18

Besides the shape of the granulosa cells surrounding the primary follicle, what is another key feature of the primary follicle?

Answer 18

there is early production of secreted glycoprotein (ZP1-4)

Question 19

within the primary follicle what type of oocyte would you find?

Answer 19

primary oocyte

Question 20

what is the secondary follicle surrounded by?

Answer 20

3-6 layers of cuboidal granulosa cells

Question 21

besides the multiple layers of granulosa cells surrounding the secondary follicle, what is another key feature of the secondary follicle?

Answer 21

there are now secretions of paracrine factors to induce local stromal cells to differentiate into thecal cells

Question 22

the progression to a secondary follicle involves increased what?

Answer 22

vascularization

Question 23

what do the secondary follicles release to increase vascularization?

Answer 23

angiogenic factors- induce the development of 1-2 arterioles

Question 24

what does the induction of the development of 1-2 arterioles generate?

Answer 24

a vascular wreath

Question 25

what are the preantral follicles dependent on for oocyte growth?

Answer 25

paracrine factors (the granulosa cells express FSH receptors)

Question 26

when does the antrum begin developing?

Answer 26

during the secondary follicle stage

Question 27

what is the term for when the oocyte is suspended in fluid surrounded by a dense mass of granulosa cells?

Answer 27

cumulus oophorus

Question 28

what happens during the antral phase of follicular development?

Answer 28

there is a 100-fold increase in granulosa cells

Question 29

what are the two distinct populations of granulosa cells that appear during the antral phase?

Answer 29

mural granulosa (stratum granulosum) and cumulus cells

Question 30

when does growth of the follicle become responsive to gonadotropins?

Answer 30

at the antral follicle stage (late secondary stage)

Question 31

what happens when LH interacts with its receptors on the theca interna cells?

Answer 31

they synthesize androgens

Question 32

what do theca interna cells synthesize the androgens from?

Answer 32

acetate and cholesterol

Question 33

what happens when the granulosa cells interact with FSH?

Answer 33

they will convert the androgens that are produced by the theca cells into estrogen

Question 34

what is the reaction that converts androgens into estrogen?

Answer 34

aromatization

Question 35

when does the oocyte become competent to complete meiosis I at ovulation?

Answer 35

at the antral stage

Question 36

what do the mural granulosa cells produce?

Answer 36

low levels of estrogen and inhibin B

Question 37

midcycle, what does the dominant follicle become?

Answer 37

a large preovulatory follicle (graffian follicle)

Question 38

what is the periovulatory period?

Answer 38

the time from onset of the LH surge to ovulation (32-36 hours)

Question 39

what occurs during the periovulatory period?

Answer 39

structural changes and changes in the steroidogenic function of the theca and mural granulosa

Question 40

what does the LH surge induce?

Answer 40

differentiation (luteinization) of granulosa cells to granulosa lutein cells

Question 41

what do the granulosa cells express at the time of the LH surge?

Answer 41

LH receptors

Question 42

during the luteinization, what are the granulosa cells inhibiting?

Answer 42

aromatase expression

Question 43

what does less aromatase expression result in?

Answer 43

a rapid decline in the androgens being converted into estradiol; this rapid decline reduces positive feedback on LH secretion

Question 44

what effect does the increased vascularization have on the granulosa cells during luteinization?

Answer 44

it increases the cholesterol availability for progesterone production

Question 45

How does the follicle wall, tunica albuginea, and surface epithelium breakdown?

Answer 45

through the release of cytokines and hydrolytic enzymes from theca and granulosa cells

Question 46

what is the antral cavity filled with during the luteal phase? and what is it called now (the transient stage between the follicle and the corpus luteum)

Answer 46

blood/ cell debris- called the corpus hemorrhagicum

Question 47

once the corpus hemorrhagicum is removed by macrophages, what is the antral cavity filled with?

Answer 47

granulosa lutein cells, cholesterol esters, theca cells, blood vessels, and white blood cells

Question 48

how long does the corpus luteum remain?

Answer 48

around 2 weeks

Question 49

what is the scar-like body that develops from the corpus luteum and what is it primarily composed of?

Answer 49

corpus albicans- primarily collagen

Question 50

what is the corpus luteum sensitive to?

Answer 50

HCG (similar in structure to LH)

Question 51

what happens if fertilization happens and the trophoblast begins secreting hCG?

Answer 51

the corpus luteum will continue producing progesterone

Question 52

what is the role of the progesterone produced by the corpus luteum during pregnancy?

Answer 52

it transforms the uterine lining into an adhesive and supportive structure

Question 53

why is the reduction of LH and secretion of inhibin by lutein cells (suppression of FSH) important if there is pregnancy?

Answer 53

it prevents the production of other follicles if there is pregnancy (so that there is not additional energy going into follicular development during pregnancy)

Question 54

how does atresia occur?

Answer 54

apoptosis (due to the decline of FSH)

Question 55

what happens to the thecal cells of follicles that have been apoptosed?

Answer 55

thecal cells persist and repopulate the cellular stroma of the ovary (known as the interstitial gland of the ovary)

Question 56

what do LH and FSH stimulate the ovary to do?

Answer 56

synthesize and secrete estrogens and progestins

Question 57

early in the follicular phase, what is the sensitivity like of the gonadotrophs to GnRH?

Answer 57

early in the follicular phase, gonadotrphs are not very GnRH sensitive; each burst of GnRH elicits only a small rise in LH

Question 58

later in the follicular phase, what is the sensitivity like of the gonadotrphs to GnRH?

Answer 58

later in the follicular phase, gonadotrophs in the anterior pituitary become much more sensitive to GnRH in the portal blood; each burst of GnRH triggers a much larger release of LH

Question 59

what enhances the sensitivity of the gonadotrophs to GnRH?

Answer 59

the high levels of estradiol that are typical of the late follicular phase

Question 60

theca cells have what type of receptors?

Answer 60

LH receptors

Question 61

granulosa cells have what type of receptors?

Answer 61

both LH and FSH

Question 62

what is required for estrogen production?

Answer 62

both LH and FSH are required

Question 63

after ovulation, what does LH act on?

Answer 63

the cells of the corpus luteum

Question 64

what is inhibin produced by in females?

Answer 64

the granulosa cells of the follicle

Question 65

what stimulates the granulosa cells to produce inhibins?

Answer 65

FSH; just before ovulation, after the granulosa cells acquire LH receptors, LH stimulates the production of inhibin by granuosa cells

Question 66

what is the action of inhibins in females?

Answer 66

it inhibits FSH production by gonadotrophs (this negative feedback loop is really necessary for selecting that dominate follicle)

Question 67

what is the role of activins?

Answer 67

they are produced in the same tissues as the inhibins but they stimulate FSH release from the pituitary cells

Question 68

what is the net effect of the estrogens and progestins feeding back to the hypothalamus and the pituitary>

Answer 68

to reduce LH and FSH release

Question 69

after the estradiol levels reach a certain threshold what happens to the HP axis?

Answer 69

it reverses its sensitivity to estrogens, it now exerts a positive feedback--> promotes the LH surge

Question 70

what is involved in the induction of the LH surge?

Answer 70

positive feedback of estrogens, progestins, and activins on the HP axis

Question 71

what happens to the LH and FSH levels as the luteal phase of the menstrual cycle begins?

Answer 71

they rapidly decrease

Question 72

what does the fall off of gonadotropin levels as the luteal phase of the menstrual cycle begins reflect?

Answer 72

negative feedback by estradiol, progesterone, and inhibin

Question 73

during the luteal phase, the rise in concentration of estradiol, progesterone, and inhibin causes what?

Answer 73

the continued decrease of gonadotropin levels midway through the luteal phase

Question 74

during the late luteal phase, the gradual demise of the corpus luteum leads to what?

Answer 74

decreases in the levels of progesterone, estradiol, and inhibin

Question 75

during the follicular phase, what is the major product of the follicle?

Answer 75

estradiol

Question 76

during the luteal phase, what are the major products of the corpus luteum?

Answer 76

progestins, although estradiol synthesis is still substantial

Question 77

what effect on the basal body temperature do the higher levels of estrogen present during the pre-ovulatory (follicular) phase of the menstrual cycle have?

Answer 77

they lower BBT

Question 78

what effect does the higher levels of progesterone released by the corpus luteum after ovulation have on basal body temperature?

Answer 78

they raise BBT

Question 79

when can the rise in BBT most commonly be seen?

Answer 79

the day after ovulation

Question 80

if the oocyte was not fertilized and pregnancy did not occur in the previous cycle, what causes the demise of the corpus luteum?

Answer 80

a sudden diminution in estrogen and progesterone secretion

Question 81

what is the proliferation and differentiation of the endometrium during the proliferative phase stimulated by?

Answer 81

estrogen (which is secreted by the developing follicles)

Question 82

what causes the induction of the synthesis of progestin receptors in the endometrial tissue?

Answer 82

estrogen

Question 83

what promotes the differentiation of the stromal cells into predecidual cells?

Answer 83

progesterone

Question 84

when is the average age of menopause?

Answer 84

51.4 years of age

Question 85

what is menopause caused by?

Answer 85

there is a reduction in estrogen, so there are low levels of inhibin; there is no negative feedback of LH and FSH, therefore there are high levels of LH and FSH seen with menopause