Bio 192 Female Reproductive Cycle

what are the stages of folliulogenesis?

primordial follicle, primary follicle, secondary follicle, tertiary follicle, mature follicle, corpus luteum

description of the primordial follicle

consists of primary oocyte surrounded by thin layer of granulosa cells

time of presence of primordial follicle

in utero (fetal)

description of primary follicle

consists of fully grown (more cytoplasm) primary oocyte surrounded by thin layer of granulosa cells

time of presence of primary follicle

in utero (fetal)

description of secondary follicle

consists of fully grown (more cytoplasm) primary oocyte surrounded by thick layer of granulosa cells and early thecal cells

time of presence of secondary follicle

in utero (fetal)

what follicles arrest until puberty?

primordial, primary, secondary follicles; each month a couple will turn into tertiary follicle, with one becoming dominant follicle that completes folliculogenesis and undergoes ovulation

description of tertiary follicle

consists of fully grown (more cytoplasm) primary oocyte surrounded by thick layer of granulosa cells surrounded by thecal cells. There is also an antrum at this stage that is filled with estrogen

description of mature follicle

consists of fully grown (more cytoplasm) primary oocyte surrounded by thick layer of granulosa cells surrounded by thecal cells. There is also an antrum at this stage that is filled with estrogen. At this stage the follicle ruptures releasing the egg leaving behind the corpus luteum

description of corpus luteum

remnants of the follicle after egg is released. Secretes lots of estrogen and progesterone

what are the events of the ovarian cycle?

follicular phase, ovulation, luteal phase

description of the follicular phase

occurs during the time when a primary follicle develops into a mature follicle and ends when the follicle ruptures (ovulation)

when does the follicular phase occur?

days 1-13

what are the corresponding phases of the uterine cycle during the follicular phase?

menstrual and proliferative

what are the estrogen levels during the follicular phase?

rising gradually with peak just prior to ovulation

what is the source of estrogen levels during the follicular phase?

granulosa and thecal cells of the follicle

what is the reason for the estrogen levels during the follicular phase?

as the follicle matures the number of granulosa and thecal cells increase, in turn increasing the amount of estrogen being produced.

what are the progesterone levels during the follicular phase?

low throughout this phase

what is the source of progesterone levels during the follicular phase?

none

what is the reason for the progesterone levels during the follicular phase?

estrogen feeds back negatively to anterior pituitary preventing high levels of LH

what are the FSH levels during the follicular phase?

gradually decreasing throughout this phase, but a spike just prior to ovulation

what is the source of FSH levels during the follicular phase?

anterior pituitary

what is the reason for FSH levels during the follicular phase?

as the follicle matures, inhibin is secreted by granulosa cells which negatively feeds back to the anterior pituitary decreasing FSH levels. Rising estrogen levels eventually cause FSH levels to spike

what are the LH levels during the follicular phase?

stays low with giant spike just prior to ovulation

what is the source of the LH levels during the follicular phase?

anterior pituitary

description of the ovulation phase

occurs when the follicular phase ends, when the follicle ruptures due to a spike in LH levels

when does the ovulation phase occur?

day 14

what are the corresponding phases of the uterine cycle during the ovulation phase?

marks the transition from proliferative to secretory phase

what are the estrogen levels during the ovulation phase?

declining

what is the source of estrogen levels during the ovulation phase?

granulosa and thecal cells of the follicle

what is the reason for estrogen during the ovulation phase?

the granulosa and thecal cells of the follicle are transitioning into the corpus luteum during which time the estrogen levels start to decline

what are the progesterone levels during the ovulation phase?

still low

what is the source of progesterone during the ovulation phase?

none

what is the reason for progesterone levels during the ovulation phase?

the follicle is transitioning to the corpus luteum but progesterone is not yet being produced

what are the FSH levels during the ovulation phase?

remains low

what is the source of FSH levels during the ovulation phase?

anterior pituitary

what is the reason for FSH levels during the ovulation phase?

as the follicle transitions to the corpus luteum, inhibin is secreted by granulosa cells which negatively feeds back to the anterior pituitary decreasing FSH levels

what are the LH levels during the ovulation phase?

returns to very low levels

what is the source of LH levels during the ovulation phase?

anterior pituitary

what is the reason for levels of LH during the ovulation phase?

estrogen levels are now low enough that the spike caused by the very high estrogen levels has reversed

description of the luteal phase

occurs when the ovulation ends, when the empty follicle has transitioned to the corpus luteum

when does the luteal phase occur?

days 15-28

what are the corresponding uterine cycle phases during the luteal phase?

secretory phase

what are the estrogen levels during the luteal phase?

russe but then by then end start to decline

what is the source of estrogen during the luteal phase?

corpus luteum

what is the reason for levels of estrogen during the luteal phase?

the corpus luteum initially produces a lot of estrogen, but as the corpus luteum starts to degenerate, estrogen production gets slower and levels start to drop

what are the progesterone levels during the luteal phase?

very high

what is the source of progesterone during the luteal phase?

corpus luteum

what is the reason for progesterone levels during the luteal phase?

the active corpus luteum secretes high levels of progesterone, until it degenerates and become the corpus albicans (dead corpus luteum)

what are the FSH levels during the luteal phase?

remains low

what is the source of FSH during the luteal phase?

anterior pituitary

what is the reason for FSH levels during the luteal phase?

the corpus luteum secretes inhibin which negatively feeds back to anterior pituitary

what are the LH levels during the luteal phase?

remains at very low levels

what is the source of LH levels during the luteal phase?

anterior pituitary

what is the reason for LH levels during the luteal phase?

estrogen levels continue to be low enough to prevent high LH levels

what are the phases of the uterine cycle?

menstrual phase, proliferative phase, secretory phase

description of the menstrual phase

as the corpus luteum degenerates into the corpus albicans, the levels of progesterone and estrogen drop dramatically causing shedding of the superficial 2/3 of the endometrium, causing the "period"

when does the menstrual phase occur?

days 1-5

what are the corresponding phases of the ovarian cycle during the menstrual phase

beginning of follicular phase

description of the proliferative phase

rising estrogen levels from the developing follicle cause thickening of the endometrium

when does the proliferative phase occur?

days 6-14

what are the corresponding phases of the ovarian cycle during the proliferative phase?

later follicular phase

description of secretory phase

continuing elevated estrogen levels from corpus luteum cause continued thickening of endometrium. Rising/high levels of progesterone secreted by corpus luteum cause increased blood vessel growth and cause secretion of glycogen from endometrium

when does the secretory phase occur?

days 15-28

what are the corresponding phases of the ovarian cycle during the secretory phase?

luteal phase