Menstrual Cycle and Ovulation Flashcards
What two organs are primarily involved in the menstrual cycle?
- uterus
- ovary
What are the stages of development of the ovarian follicle? (4)
- primordial follicle
- primary follicle
- secondary follicle
- graafian (mature) follicle
How does the primordial follicle differentiate from the primary follicle? (4)
- simple squamous becomes cuboidal
- follicle begins to produce glycoproteins (ZP1, 2, 3, 4)
- vascular wreath forms (cuz angiogenic factors)
- zona pellucida develops
What are granulosa cells analogous to? What receptors do they express?
- sertoli cells
- FSH receptors AND LH receptors
What are thecal cells analogous to? What receptor do they express? What is their major product?
- Leydig cells
- LH receptors
- Androstenedione
What happens during the antral phase of follicle development? (3)
- oocyte becomes suspended in fluid
- cumulus oophorus appears
- granulosa cells multiply exponentially
What are the two populations of granulosa cells during the antral phase? What do they do?
- Mural granulosa = make steroid hormones
- cumulus cells = maintain gap/adhesion junctions with oocyte
What is the role of the theca interna during the antral stage?
synthesizes androgens from acetate and cholesterol, mostly androstenedione
What is the role of the granulosa cells during the antral stage?
Convert androgens from thecal cells to estrogens
At what point do large antral follicles go through meiosis a second time?
after the LH surge
How is meiosis arrest achieved?
By maintained elevated cAMP
How does sensitivity to FSH aid in selection of a follicle?
Only the biggest follicle with the most FSH receptor will become dominant, the others atrophy
What happens during the preovulatory period? (3)
- the corpus luteum is formed
- more progesterone is produced
- there are structural changes to the follicle
What effect does luteinization have on theca and granulosa cells?
- granulosa cells become granulosa lutein cells
- theca cells become theca lutein cells
What structural changes does the LH surge induce in the ovary/oocyte? (4)
- release of cytokines and hydrolytic enzymes break down follicle wall, tuniga albuginea and surface epithelium
- cumulus-oocyte complex detaches (frees egg)
- basal lamina of mural granulosa degrades
- oocyte progresses to metaphase II
What happens during the luteal phase in regards to the ovary?
- antral cavity fills with blood/cell debris
- granulosa lutein cells collapse into antral cavity
How long does the corpus luteum remain?
- 14 days approximately unless rescued by hCG
What does the corpus luteum do?
- Produces increasing progesterone, which transforms uterine lining into adhesive and supportive structure
What effect does estrogen and progesterone have on LH?
They inhibit it to basal levels
What do lutein cells secrete? What does it do?
- inhibin A
- suppress FSH
What is follicular atresia?
When the ovarian follicle apoptoses
What are thecal cells also referred to as? Why?
- The interstitial gland of the ovary
- because they repopulate the cellular stroma of the ovary after follicular atresia
What stage of the follicular phase are gonadotrophs more sensitive to GnRH during? Why?
- the late follicular phase
- because high levels of estradiol in late phase enhance sensitivity of gonadotrophs to GnRH
What specifically stimulates granulosa cells to produce inhibins?
LH and FSH
What do inhibins do? What cells are they released from?
- Inhibit FSH production by gonadotrophs
- released from sertoli and granulosa cells
What do activins do? Where are they secreted from?
- Stimulate FSH release from pituitary cells
- granulosa cells
What level of estrogens stimulate negative feedback?
low and high levels
What effect do estrogens and progestins have on hypothalamus and pituitary?
a negative feedback effect
What level of progestins stimulate negative feedback?
High levels
When does the switch to positive feedback occur? What does it cause?
- Near the end of the follicular phase
- the LH surge
What two hormones promote the LH surge?
Estrodiol, progesterone
What is unique about the stimulatory effect of activins on FSH?
it is INDEPENDENT of GnRH action
What peaks during the follicular phase? (3)
- estradiol
- LH
- FSH
What peaks during the luteal phase? (3)
- progesterone
- estradiol
- inhibin
What leads to decrease in hormonal levels during late luteal phase?
degradation of the corpus luteum
What is the major product of the follicle during the follicular phase?
estradiol
What synthesizes estrogen during the luteal phase?
corpus luteum
What causes lowered BBT during follicular phase?
higher levels of estrogen
What causes higher BBT during luteal phase?
higher levels of progesterone
What causes drop of BBT during onset of menstruation?
degradation of the corpus luteum
What happens to the endometrium when the corpus luteum degrades?
The tissue breaks down, leading to bleeding (was maintained by corpus luteum)
What happens to the endometrium during the proliferative phase? (2)
- proliferation of the basal stromal cells in zona basalis
- proliferation of epithelial cells from other parts of uterus
What hormone is proliferation and differentiation of endometrium stimulated by?
estrogen from developing follicles
What does estrogen induce synthesis of in endometrial tissue?
progestin receptors
What happens to the endometrium during the secretory phase? (4)
- vascularization of endometrium increases
- glycogen content increases
- endometrial glands become engorged with secretions
- stromal cells differentiate into predecidual cells
What hormone promotes the differentiation of stromal cells into predecidual cells?
PROGESTERONE
What physiological symptoms does PCOS cause? (4)
- hyperandrogenism
- anovulation
- polycystic ovaries
- infertility
What hormonal changes do individuals with PCOS experience? (3)
- elevated LH
- lowered FSH
- elevated testosterone
What is the classic presentation of a patient with PCOS?
Young, obese, hirsute females of reproductive age with oligomenorrhea or secondary amenorrhea, possibly infertility
What is Turner syndrome the most common cause of?
congenital hypogonadism
What is Turner syndrome often caused by?
complete absence of second X chromosome
How do individuals with Turner syndrome typically appear, genitalia-wise?
- external and internal genitalia are female
What is the common presentation of a patient with Turner syndrome? (7)
- short
- delayed puberty
- webbed neck
- nonfunctional ovaries
- skeletal abnormalities
- learning disabilities
- lymphedema of hands/feet
What is menopause defined as?
Occurs 12 months after last menstrual period
What is menopause caused by?
- reduced estrogen
- low levels of inhibin
What are the levels of LH and FSH? Why?
Elevated LH and FSH caused by lack of negative feedback from inhibin, estrogen
What are the signs and symptoms of menopause? (9)
- irregular periods
- vaginal dryness
- hot flashes
- night sweats
- sleep problems
- mood changes
- weight gain, slowed metabolism
- thinning hair/ dry skin
- loss of breast fullness
What are some treatments to manage the symptoms of menopause? (4)
- estrogen therapy
- vaginal estrogen
- low-dose antidepressants
- gabapentin
