Follicular Physiology Flashcards
What are the 4 major events during the follicular phase?
Rising gonadotropin release from anterior pituitary
Follicle growth
Sexual receptivity
Ovulation
What is the dominant hormone during the follicular phase?
Estrogen
What role does the tonic center play in the follicular phase?
Small pulses of GnRH stimulates release of FSH and LH
What role does the surge center play in the follicular phase?
Increasing levels of estrogen lead to release of a large quantity of GnRH which causes release of LH resulting in ovulation.
What hormone does the dominant follicle release to ensure it’s the main event?
Inhibin
What hormone does inhibin have a negative effect on?
FSH to make sure not other follicles are being stimulated
What hormone does the dominant follicle release to give positive feedback to the hypothalamus causing a turnover to the surge center?
Estradiol
What does the release of estradiol from the dominant follicle cause?
Preovulatory LH surge from the surge center
During what phase of estrous cycle does FSH peak?
Estrus
During what phase of estrous cycle does Progesterone peak?
Diestrus
During what phase of estrous cycle does Estrogen peak?
Estrus
During what phase of estrous cycle does LH peak?
Estrus
What are the 4 parts of follicular dynamics?
Recruitment
Selection
Dominance
Atresia
What is Recruitment?
Recruitment of small antral follicles
What is Selection?
Follicles selected from recruited follicles
What is Dominance?
Selected follicles that do not undergo atresia
NOTE: These follicles undergo ovulation.
What is Atresia?
Follcles that do not proceed to dominance.
On palpation, what would a dominant follicle feel like?
Feels like a blister.
On palpation, what would a CL feel like?
A bump on the ovary.
How do we cause superovulation for embryo transplant?
During the second wave or follicular dynamics (in diestrus) give lots of GnRH to cause a release of LH to lyse the CL and allow more follicles to develop and ovulate.
What are the general levels of the 4 major hormones during recruitment?
High FSH
Low LH
No inhibin
No E2
What are the general levels of the 3 major hormones during selection?
Low FSH
Moderate LH
Low inhibin
What are the general levels of the 3 major hormones during dominance?
Low FSH
High LH
High inhibin
Where does the estrogen come from?
LH binds to theca interna cells, producing testosterone which goes into the granulosa cells. When FSH binds to the granulosa cells, they convert testosterone to estrogen.
How does the LH surge help get the oocyte to a place where it can be fertilized?
Meiosis inhibition is removed and the 4N oocyte is allowed to become 2N. At ovulation, a second meiotic division brings it to a 1N and the oocyte is now ready to be fertilized.
What is strange about ovulation in dogs?
They ovulate a primary oocyte (4N).
