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SFIV Test 3 > Female Sex Hormones > Flashcards

Female Sex Hormones Flashcards

1
Q

What are the principal steroid hormones secreted by the adult ovary?

A

Estradiol

Progesterone

Androstenedione

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2
Q

What is the primary source of estrogens in the non-pregnant adult?

A

Maturing follicle

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3
Q

What is estradiol (E2)?

A

Principal ovarian estrogen

Most potent

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4
Q

What is estrone (E1)?

A

Formed from estradiol and androstenedione by peripheral conversion

Fat is a major source of aromatase activity

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5
Q

What is estriol (E3)?

A

Weak estrogen

Levels are only usually measured during pregnancy

Placenta synthesized large amounts of E3 during pregnancy

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6
Q

What two cells in the follicle are responsible for estrogen synthesis?

A

Thecal cells

Granulosa cells

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7
Q

What are thecal cells?

A

Close proximity to blood vessels, source of LDL

Have enzymes to synthesize androgens

Do not produce aromatase, so can’t convert androgens to estrogens

Androstenedione production

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8
Q

What are granulosa cells?

A

Unable to synthesize androgens

Have high aromatase activity, so they can convert androgens from thecal cells to estrogens

Also expresses 17B-HSD, which converts estrone to estradiol

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9
Q

Describe the hormonal control of thecal and interstitial cells of the ovary.

A

Possess LH receptors

LH induces androgen biosynthesis via cAMP pathway

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10
Q

Describe the hormonal control of granulosa cells?

A

Expression of aromatase induced by FSH via cAMP pathway

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11
Q

What are progestins?

A

Steroids that promote gestation

Progesterone is the most potent

Principal sourc is the corpus luteum

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12
Q

What is the principal circulating androgen in women?

A

Testosterone

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13
Q

What are the three phases of the reproductive cycle?

A

Follicular phase

Ovulatory phase

Luteal phase

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14
Q

What is the follicular phase?

A

Begins with the onset of menstrual bleeding

Preovulatory follicle develops within the ovary

Estradiol primary hormone

Corresponds to menstrual and proliferative phases of the endometrial cycle

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15
Q

What is the ovulatory phase?

A

Lasts approximately 36 hours and culminates in ovulation

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16
Q

What is the Luteal phase?

A

13-14 days

Corpus luteum and ovary secretes both progetsone and estradiol

Corresponds to the secretory phase of the endometrial cycle

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17
Q

What is the primordial follicle?

A

Primary ooctye surrounded by a single layer of poorly differentiated pregranulosa cells

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18
Q

Describe recruitment of primordial follicles

A

Begins in fetal life and continues in wave-like fashion until the supply is depleted at menopause

19
Q

What occurs to follicular growth prior to puberty?

A

Follicular growth occurs but the process is arrested in an early stage

Follicle undergoes atresia

20
Q

What is a primary follicle?

A

Primordial follicle leaves the pool of inactive follicles

Zona pellucida forms around the oocyte

Oocyte and granulosa cells increase in size

21
Q

What extracellular proteins are secreted by the oocyte during the formation of a mature preantral follicle?

A

ZP1, ZP2, ZP3

Provide species-specific binding sites for sperm cells

22
Q

How do the granulosa cells mature during mature preantral follicle formation?

A

Oocyte releases paracrine factor that stimulate the growth and differentiation of the granulosa cells

Granulosa cells begin to express FSH and estrogen receptors

23
Q

What is the difference between early antral follicles and Larger antral follicles?

A

Early antral follicles - responsive to FSH, but considered to be FSH independent

Large antral follicles - Highly dependent on FSH for growth and survival

24
Q

What factors promote atresia in oocytes and granulosa cells?

A

Tumor necrosis factor a (TNFa)

Androgens

IL-6

25
Q

What are the two populations of granulosa cells that appear due to the swelling of the antral cavity?

A

Mural cells - close to thecal layer, engaged in steroidogenesis

Cumulus cells - surround oocyte, facilitate the capture of the oocyte by the ciliated fallopian tubes

26
Q

What is the gonadotropin-dependent phase of follicular growth?

A

Cohort of growing antral follicles is recruited, but only dominant follicle survives

Survival of follicles that enter this stage of rapid growth is dependent upon FSH

27
Q

When does cyclic recruitement occur?

A

During the late luteal phase of the preceding cycle

28
Q

When is the dominant follicle selected?

A

Early follicular phase of the current cycle

29
Q

What indicates the presence of a dominant follicle?

A

Dramatic increase in circulating estradiol levels

Ovulation occurs about 10-14 days after a follicle is selected

30
Q

What is the role of FSH during the follicle selection process?

A

FSH stimulates granulosa cell proliferation and estradiol synthesis

Estradiol works syntergistically with FSH to promote granulosa cell proliferation

Estradiol and inhibit have a negative feedback effect on FSH release by the anterior pituitary

31
Q

How does the dominant follicle inhibit the development of less mature follicles in the cohort?

A

Through the negative feedback by E2 on FSH release

The other follicles will undergo atresia

FSH containes within the follicular fluid of the dominant follicle helps it sustain the falling FSH levels

32
Q

Why can granulosa cells respond to the LG surge?

A

FSH induces the expression of LH receptors

33
Q

What factors influence the growth of the dominant follicle in the presence of declining levels of FSH?

A

More FSH receptors

Produces IGF-1, enhancing responsiveness to FSH

FSH induces LH receptor expression

Follicular fluid has FSH

Better developed vascular supply

34
Q

What is the stigma?

A

Poorly vascularized bulge in the ovary created by the pressure of the follicle

35
Q

What is cumulus expansion?

A

Increase in size of the cumulus-oocyte complex due to secretion of ECM components in response to LH stimulation

36
Q

What s the signal required to induce ovulation?

A

LH surge

Result of a positive feedback effect of estradiol on the pituitary and hypothalamus

37
Q

What are the specific actions of LH on the preovulatory follicle?

A

Release of hydrolytic enzymes

Expression of COX-2 and progesterone receptors

Resumption of meiosis via growth factor release

Promotes cumuls expansion

Promotes reorganization of follicle into the corpus luteum

38
Q

What is the corpus luteum formed from?

A

Remnants of the ruptured follicle

Mural granulosa cells and thecal cells differentiate into granulosa- and thecal-lutein cells

39
Q

How does LH promote angiogenesis?

A

Inducing the granulsa-lutein cells to secrete VEGF

40
Q

Why are granulosa-lutein cells able to obtain cholesterol from circulating LDL and HDL?

A

LH induces breakdown of basal lamina

LH induces LDL and HDL receptor expression

41
Q

How does LH induce steriodogenesis in granulosa-lutein cells?

A

Induces expression of StAR

Since these cells do not express androgen synthesis enzymes, they release progesterone

42
Q

What causes luteolysis?

A

Decline in LH production due to negative feedback effects of estrogen and progesterone

43
Q

What occurs to the corpus luteum in pregnant women?

A

Corpus luteum is maintained due to human chorionic gonadotropin (hCG)

SFIV Test 3 (14 decks)

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