Chapter 8: Reproductive Cyclicity: the follicular phase Flashcards
What has to happen for the onset of follicular development
lysis of CL
Gonadotropin hormonal cascade
increase in FSH and LH -> increased follicular growth -> increased estradiol -> estrus caused -> GnRH surge -> LH surge -> Oocyte maturation -> Ovulation
Where does GnRH come from?
Hypothalamus
Where is GnRH secreted
PPP
Where are FSH and LH secreted
secondary Portal plexus
purpose of PPP system
Channel where GnRH can act and not get diluted by systemic circulation
center with small spikes of GnRH that occur infrequently
Tonic center
center with high amplitude GnRH release
Surge center
What causes surge center to release GnRH
when the threshold of E2 is met. (pre-ov surge)
How often do the small spikes of GnRH occur in the follicular phase?
1.5-2 hrs
How often do the small spikes of GnRH occur in the luteal phase?
4-8 hrs
2 mechanisms that cause LH surge
positive feedback and neural reflex
what type of animals depend on positive feedback for LH surges?
spontaneous ovulators
what type of animals depend on neural reflex for LH surges?
induced ovulators
selectively supresses secretion of FSH
inhibin
How does Inhibin affect LH
it doesn’t affect LH
Aside from Inhibin, what also has a negative feedback on FSH
Estradiol
stages of the estrous cycle
diestrus, proestrus, estrus, metestrus
stages of the Estrous cycle in the Follicular phase
proestrus and estrus
stages of the estrous cycle in the luteal phase
metestrus and diestrus
types of cells in antral follicle
theca interna & granulosal cells
T or F: Theca interna and granulosal cells have a role in E2 synthesis
True
Which cells have receptors for LH
theca interna
when LH binds with its receptors on Theca interna cells, what results
cascade results in T4 production which enters granulosal cells
What cells have FSH receptors
Granulosal
what happens when FSH binds to its receptor on granulosal cells?
different protein kinase activate aromatase system to convert T4 to E2
What does E2 do in the female repro tract
increase blood flow, increase edema, increase mucus secretion, increase WBC’s, smooth muscle motility, growth of uterine glands, increases repro behaviors
phonation, “mating call” activity
Lordosis
follicular atresia
depletion of follicles
Lack of cyclicity
menopause
physical actions by the body to prepare for ovulation
elevated blood flow, breakdown of connective tissue around follicle, and ovarian contractions
local elevated blood flow
hyperemia
what controls hyperemia
histamine and PGE2 (prostaglandin E2)
what cells become edematous
theca interna
What does the preovulatory LH surge cause?
increase in PGE2, PGF2a, shift from E2 to P4, weakening of surface epithelium, gap junction breakdown.
what does PGF2a cause
contraction of smooth muscle within ovary
apex of follicle
stigma
What does P4 do to the follicle
promote collagenase which breaks down the follicular wall
when does the 1st meiotic division and the formation of the 1st polar body happen?
prior to ovulation
what is the result of the 2nd meiotic division
haploid
when is the 2nd polar body formed
post ovulation
