Female Reproductive System Review (Michels) - MT Flashcards
Describe LH secretion patterns (day and night) during a woman’s:
- Childhood
- Puberty (10-14 years)
- Reproductive years (14-50 years)
- Menopausal stage (50+)
- childhood: scant, little day and night
- Puberty: low during the day, increased/pulsatile during the night
- Reproductive years: Constantly pulsatile day and night
- Menopause: High pulsatile levels day and night
FSH and LH levels in a woman peak during what times between the time of conception of herself as a fetus and her puberty? (2x)
- between the 2nd and 3rd trimesters
- between birth and 6 months
What is occuring on day zero of a woman’s menstrual cycle between the pituitary and ovaries?
- events in pituitary
- events in ovary
- Pituitary responds to falling levels of Estradiol and Progesterone by increasing FSH secretions
- Corpus luteum dies, leading to a decline in Estradiol and Progesterone
What is occuring between day zero and day 13 of a woman’s menstrual cycle between her pituitary and ovaries?
- Pituitary events (2x)
- Ovary events (2x)
*hint: how does the selection of the dominant follicle occur?
- Pituitary
b - Estradiol and inhibin negatively feed back on FSH
d - High Estradiol has positive feedback on gonadotropes –> LH and some FSH surges
- ovaries
a - FSH recruits a cohort of large antral follicles to enter rapid growth phase. Follicles secrete low amounts of E and inhibin.
c - Declining FSH levels cause atresia of all but 1 follicle –> selection of dominant follicle which produces high levels of Estradiol
On day 14 of a woman’s menstrual cycle what is occuring with her pituitary-ovary cross talk?
*hint: ovulation is occuring and corpus luteum has formed at this point
a - LH surge induces metabolic maturation, ovulation and luteinization. Corpus luteum produces high Progesterone and Estradiol + inhibin
The follicular phase occurs when in the average 28 day cycle for a mature fertile woman?
Luteal phase?
follicular 0-14 days
Luteal 14-28 days
are the stages of follicular development?
(x6)
- Primordial follicle
- primary follicle
- secondary preantral follicle
- small antral follicle
- large, recruitable antral follicle
- dominant follicle at ovulation
Primordial follicles grow into primary follicles and then secondary pre antral follicles. This process is identified as the initiation and gonadotropin independent growth phase.
What is occuring to the follicles in this phase regarding:
- follicular growth
- growth regulation
- Is growth dependent or independent of pituitary gland?
1 - Follicles enter early growth
2 - This growth is regulated by paracrine signaling b/t oocyte and follicle cells and b/t growing and resting follicles
3 - growth is Independent from pituitary gland
The secondary preantral follicle stage, small antral follicle and large recruitable antral follicle stage are mediated by the Basal growth phase.
- follicles are dependent on what molecule to grow during this phase?
- what is the follicular sensitivity to growth stimulation during this phase?
- Follicles are dependent on gonadotropins,
- … but have low sensitivity and are not influenced by fluctuations associated with menstrual cycle.
Once follicles reach the stage where they are large and recruitable antral follicles, they are said to enter rapid growth phase. It takes about 14 days for the dominant follicle to be selected at ovulation.
- What are the large recruitable antral follicles sensitive to in this 14 day period of “Hunger Games” like trials?
- How do follicles avoid atresia (being killed, like Rue)?
- Follicles are extremely sensitive to increase in FSH at the end of menstrual cycle and
- extremely dependent on FSH to avoid atresia
Time table for follicular development:
- Time it takes for primordial follicle to become primary and then secondary preantral follicle?
- time it takes secondary preantral follicle to become small antral follicle?
- time it takes small antral follicle to become large recruitable follicle?
- time it takes to select a dominant follicle from the pool of large recruitable antral follicles?
- >3 months
- 25 days
- 45 days
- 14 days
Large recruitable antral follicles contain what two types of cells?
- mural granulose cells
- cumulus cells
Mural granulose cells highly ______ and differentiate into what?
- highly Steroidogenic
- corpus luteum
Cumulus cells are released with ____ upon ovulation and facilitate what vital process?
- OOcyte
- facilitate oocyte capture by oviduct
OOgonium gamete formation into a haploid ovum occurs via meiosis.
- Why are primary oocytes arrested at prophase I?
- what actively keeps primary oocytes arrrested in prophase I?
- Why are secondary oocytes arrested at metaphase II?
- when is the first polar body extruded?
- When does the secondary oocyte complete meiosis and extrude the 2nd polar body??
- levels of proteins required for completion of meiosis are too low, needs adequate levels of CDK1 and Cyclin B to complete meiosis
- High cAMP levels generated by GPR3 produced by oocyte actively maintains arrest
- production of MAPK pathway proteins arrest oocyte at metaphase II
- upon completion of meiosis I
- upon fertilization, this forms the haploid ovum
Folliclar cells include what 2 types of cells?
- Theca cells
- Granulosa cells
- Theca cells respond to what molecule, and as a result produce _______?
- Granulosa cells respond to what molecule, and as a result produce _______?
- *hint: Hypothalamus starts production of these molecules by releasing ______.
- theca cells respond to LH and produce Androgen (androstenedione)
* thecal cells have low levels of 17beta hydroxysteroid dehydrogenase and therefore do not produce large amounts of testosterone
- granulosa cells respond to FSH and produce Estrogen
- GnRH
- In the second half of follicular phase, FSH induces expression of _______ on mural granulosa cells.
- What does this allow to occur?
- FSH induces LH receptor expression on mural granulosa cells
2 allows mural granulosa cells to respond to both LH and FSH and respond to LH surge prior to ovulation.
What type of follicular cells produce inhibins?
granulosa cells
Androgen derived estrogen, estrogen, and inhibins produced by granulosa cells negatively feedback on what hormones?
- LH and FSH production
- At the end of follicular phase what happens to the feedback loop between estrogen, LH, and FSH?
- what event does this trigger?
- The negative feedback of estrogen becomes positive feedback and produces an LH and FSH surge.
- This triggers the LH surge that resulting ovulation
In the luteal phase Theca and granulosa cells promote the production of Estrogen which stimulates an LH surge which stimulates the corpus luteum luteal cells (formed after ovulation) to produce what?
- Lots of progesterone and some estrogen
Luteinization is the process whereby mural granulosa cells experience transient inhibition of CYP19 expression and estrogen production.
What does this do to the positive feedback loop?
turns it off
so that estrogen and progesterone do not simulate LH and FSH release
What is the lifespan of the corpus luteum?
What can prolongs its survival?
- about 14 days
- HCG inflammatory event can rescue it by revascularizating it into the corpus albicans
Estrogen has what effects on the oviducts?(x5)
- Endosalpinx epithelial size
- blood flow
- oviduct specific glycoproteins
- ciliogenesis
- mucus, muscular tone
What does progesterone do to the oviducts? (x3)
- decreases epithelial size
- deciliation of oviducts
- decreases mucus
- relaxes muscular tone
The uterine lumen is made of the endometrium and myometrium. The endometrium is then divided into the functional zone and basal zone.
what happens to the functional zone during menstruation?
It is lost