Menstrual Cycle Flashcards
In males, negative feedback of FSH and LH is from what?
what about in females? (caveat?)
Testostorone
Estrogen but it also positive feedback as well.
Puberty in the girls involves:
Thelarche?
Adrenarche?
Menarche?
breast development
increase in adrenal androgen secretion
beginning of menstrual cycles
Gonadotropin levels through the life of the female?
increases in gonadotropin during the 2nd trimester (mostly FSH)
early postnatal time (mostly FSH)
puberty they rise, leading to the reproductive years and monthly surges of LH
Menopause (high of both but more FSH.. low estrogen removes negative feedback so elevated gonadotropin)
What’s to note about the oscillatory patterns of GnRH secretion in puberty for females?
somehow it starts in the REM sleep of females. that’s when we start seeing higher levels and in a pulsatile manner
What does the ovarian cycle consists of?
Endometrial cycle?
Follicular + Luteal
Menstrual phase (Menses), proliferative, secretory
Oocyte –> graafian follicle?
Primary oocyte that has been replicated.. it’s arrested in meiosis 1 prophase 1.
then the follicle grows and a mix of cells that surround the oocyte and form the follicles.
the most undeveloped stage of the follicle is the “primordial follicle”.. it’s surrounded in cells called “pregranulosa cells”
when they differentiate enough to become granulosa cells, we consider that follicle the primary follicle. (UNILAMINAR –> one layer of granulosa)
follicle continues and you get additional layers of granulosa cells and theca cells are going to show up… this is the secondary follicle (MULTILAMINAR PRIMARY FOLLICLE)
then we get a small antrum, which helps distinguish between secondary and early tertiary follicle.. also see a ton of granulosa cells, and closest to the oocyte is called the corona radiata (also have theca interna and externa) (CALLED SECONDARY FOR ANATOMY)
Graafian follicle –> bigger antrum, corona radiata still there, we also have a cumulus oophorus which connects the oocyte to the wall.. theca cells are proliferating and we have the theca interna and theca externes.
granulosa cells are most similar to what in males?
sertoli cells
closely tied to the oocyte providing nutrients.
at the LH surge, what happens to the gamete?
when does this happen?
we pass prophase one and we go through meiosis and it’s arrested one more time in metaphase of meiosis 2.
going from early tertiary follicle (2ndary) to Graafian follicle
When do we go from 2N to N for the gamete?
what else forms during this process?
second meiotic division is completed upon fertilization.
1 egg and 2-3 polar bodies are going to happen when this happens.
What marks the dependency of gonadotropin?
the development of the antrum
what’s happening constantly in the woman?
what is chosen?
what happens to the ones that aren’t chosen?
there are going to be different follicles at different stages.
there are going to be some mix of primary and secondary (antrum or no antrum) and it needs to be ongoing because the development of the follicle doesn’t happen fast, so there should be this constantly going on so selection can happen faster
the ones that are selected are the antrums are bigger.
the rest that doesn’t qualify or meet the quota are lost through atresia.
What’s the difference in antral follicles with their size and dependency on FSH?
early antral follicles are dependent on FSH for normal growth –> secrete very low levels of estrogen which is important to the negative feedback
large antral follicles (the ones we want to select) are HIGHLY dependent on their growth and sustained viability.
What are mural granulosa cells?
what’s to note about androgens and this?
what happens to this and the theca cells after ovulation?
in the growing antral cells, not only do we have theca cells that are going to be androgens to be converted to estrogen, but we also are dependent on the sterotidogenic activity of Mural Granulosa cells
as they grow, that population becomes highly steroidogenic.
this population are going to be remaining after ovulation and differentiate to corpus luteum
Dominant follicle?
as FSH levels drop, the rapidly growing follicles progressively undergo atresia until there is one survivor left.
the largest follicle with the MOST FSH receptors of the recruited crop becomes the dominant follicle!
Periovulatory period?
what happens at the start of the periovulatory period and goes throughout the process of ovulation?
what happens during this?
time from the onset of the LH surge to ovulation –> lasts 32-36 hours
at the same time, we’re going to have that with the LH surge there is luteinization
changing theca and granulosa cells to produce tons of progesterone, along with estrogen, within a few days after ovulation
induces dramatic changes in the dominant follicle that involves its rupture, ovulation of the corona radiate-oocyte complex, and biogenesis of the corpus luteum from what remains.
what happens to the dominant follicle during the periovulatory period?
1) where does the ovum do as it goes closer to the wall?
2) what happens to this structure?
3) what does the antrum become continuous with then?
follicle presses against the wall of ovary and forms bulge called the STIGMA
LH surge induces release of cytokines and hydrolytic enzymes from the theca and granulosa cells –> breaks down follicle wall, tunica albuginea, surface epithelium
antrum cavity becomes continuous with peritoneal cavity
what happens to the basal lamina of the mural granulosa cells during the periovulatory period
what do granulosa cells produce to increase the blood supply to the new corpus luteum
enzymatically degraded and blood vessels and outer lying theca can push into the granulosa cells.
angiogenic factors including Vascular Endothelial Growth Factor, angiopoietin 2, basic fibroblast growth factor
Corpus Luteum life span?
what can save it? how long does it last then?
What is it highly similar to? how so?
life span of 14 days unless rescued by human chorionic gonadotropin (hCG) which originates from the implanting embryo from part of the placenta.
if rescued, corpus luteum will remain viable for as long as the pregnancy.
hCG is highly similar to LH.. it can produce high levels of progesterone
Follicular Atresia, when does this happen?
what’s lost?
What persists?
occurs at any time of the development
losing granulosa cells and oocytes that weren’t selected. (makes sense since they’re providing nutrients for the gametes
Thecae cells persist and repopulate the cellular storm of the ovary
throughout the lifespan, how many dominant follicles are going to be ovulated?
400-500
Summary of folliculogenesis (includes all 3 phases)
follicular phase –> recruitment/growth of atrial follicles –> selection of dominant follicle –> growth of dominant follicle until ovulation
LH surge causes –> ovulation
Luteal phase –> hormonal secretion by the corpus luteum
What causes the LH surge?
estrogen, positive feedback mechanism from estrogen from the dominant follicle
Follicle needs what to complete its development? what happens to these levels as time goes on?
when does the follicle growing technically start and end?
what do granulosa cells increase the production of and what does this do in turn?
FSH.. they decline but it selects for the cells for high sensitivity to find the dominant follicle.
start of menses, end on LH surge (around 14 days)
estradiol –> stimulates endometrium to undergo continuous growth and maturation
rapid rise of estradiol triggers the surge of LH, which causes ovulation
what does the increase of estradiol from the granulosa cells match up with in the endometrial cycle?
proliferative phase
rapid rise of estradiol triggers the surge of LH, which causes ovulation
Luteal phase?
what do luteal cells produce? what does this lead to?
what does it coincide with in the endometrial phase?
follicle transforms into a corpus luteum
luteal cells produce progesterone and estrogen and inhibin, which stimulate further endometrial growth and development
secretory phase
Inhibin in females is going to be coming from what source of cells?
what does it feed too?
What receptors do they have?
granulosa cells.. which are feeding into anterior pituitary to regulate FSH.
granulosa cells have receptors for FSH and LH