Follicular Phase Flashcards
What are the two subphases of the follicular phase?
proestrus and estrus
What are the concentration trends of the major hormones (P4, E2, LH, and FSH) during proestrus?
P4 plummets and reaches its lowest concentration, E2, LH, and FSH all start to rise
What are the concentration trends of the major hormones (P4, E2, LH, and FSH) during estrus?
E2, LH, and FSH reach their peaks, P4 is at its lowest point
Which of the four major hormones is most responsible for estrus, especially the physically manifestations of estrus?
the peak of E2, LH, and FSH
What is the source of E2?
follicle
What is the source of P4?
the corpus luteum
What is the source of LH and FSH?
anterior pituitary
What are follicular waves?
waves of maturation for follicular development
What are follicular cohorts?
a group of follicles that are physically grouped together for follicular development
What is super ovulation?
the process in which the ovary is pharmacologically nudged to ovulate more than 1 ovum
What are cystic ovaries?
a pathological situation in which the follicles fails to ovulate
What are the changes to the ovary that accompany the follicular phase?
a group of follicles are physically grouped and mature into small follicles, a portion of them undergo atresia while another portion matures into medium follicles, a small number of the medium follicles mature into large follicles, one of the large follicles is dominant. as the follicle develops a fluid filled sac enlarges and encompasses the ovum and once it is completely surrounded it is released from the ovary
What is the relationship between LH and theca and granulosa cells?
LH activates receptors on these cells and stimulates the synthesis of testosterone in theca cells
What is FSH’s role in production of estrogen?
it activates aromatase which converts testosterone into estrogen
Why are there differing amounts of LH and FSH present during the follicular phase even though the release of both is equally stimulated by GnRH?
FSH is required for the recruitment of follicles, once that is complete, the release of FSH is inhibited. LH is required for the maturity of follicles so its release continues even though FSH has been inhibited
What are the seven feedback mechanisms occuring during the follicular phase?
1) P4 prevents GnRH release (not depicted) at the hypothalamus
2) GnRH promotes LH and FSH release at the AP.
3) LH and FSH promote E2 synthesis in the follicle
4) E2 promotes GnRH release from the hypothalamus.
5) E2 promotes its own synthesis at the follicle (granulosa cell).
6) Inhibin prevents FSH release from the AP.
7) E2 promotes the LH surge from the AP (not depicted) at ovulation.
