Follicular Physiology Flashcards
Which species is seasonally polyestrus?
Horse
What are the 4 major events of the follicular phase?
- Rising levels of GnRH release from anterior pituitary
- Follicular growth/prep for ovulation
- Sexual receptivity
- OVULATION
What is the major hormone in the Follicular phase?
Estrogen!
What are the two main “players” of the follicular phase?
Tonic & Surge center of the hypothalamus
What “turns on” the surge center of the hypothalamus?
Once E2 reaches a threshold level
The tonic center releases small amplitude pulses of _____ that stimulate the release of ___ & ___ from the Anterior Pituitary.
The tonic center releases small amplitude pulses of GnRH that stimulate the release of FSH & LH from the Anterior Pituitary.
FSH & LH cause the growth & development of ______, which produce______, on the ovary
Follicles, Estrogen
The surge center responds in a positive feedback fashion to the increasing levels of _____ from the follicle in the absence of _____ to release large quantities of _____.
Estrogen, Progesterone, GnRH
The surge center responds in a positive feedback fashion to the increasing levels of ESTROGEN from the follicle in the absence of PROGESTERONE to release large quantities of GNRH.
The large quantities of GnRH from the surge center causes the preovulatory ___ surge which leads to ____.
LH, Ovulation
The large quantities of GnRH from the surge center causes the preovulatory LH surge which leads to OVULATION.
The proestrual follicular development, in response to FSH & LH, allows the follicle to release estrogen & _____ which then causes a decrease in _____.
Inhibin, FSH
The increase in estrogen from follicular development has positive feedback on the _______.
Surge center of the hypothalamus
The increase in estrogen from follicular development has negative feedback on _______.
FSH
Progesterone has a _____ feedback at the level of the hypothalamus on GnRH.
Negative
What happens to the following hormone’s levels during the follicular phase?
P4:
E2:
FSH:
LH:
P4: decrease
E2: increase
FSH: increases then sharply decreases before ovulation
LH: Increases at same rate as FSH and then increases sharply at the same time FSH decreases
Process of choosing of small antral follicles from ovarian pool
Recruitment
Process of choosing from the recruited follicles
Selection
Selected follicles that do NOT undergo atresia but instead undergo ovulation
Dominant follicles
Where the antrum disappears from an Antral follicle
Atresia
What is the name, size , and amount of estrogen produce by the follicles that are recruited from the ovarian follicular pool?
F1
What is the name, size , and amount of estrogen produce by the follicles that are selected from the F1 group?
F2
5-12 mm
Medium amount of E2
What is the name, size , and amount of estrogen produce by the follicles that are dominant from the F2 group?
F3
>12 mm
Larges amount of E2
What is the difference in the number of F3’s in a dog vs. a horse?
Horses only have 1, maybe two since they bear a single offspring
Dogs have multiples since they are litter bearers
How does an F3 feel different from a CL?
F3 is more fluidy while a CL feels more like a gummy bear head and protrudes out more
What are the levels of FSH, LH, Inhibin, and E2 during Recruitment?
FSH: High
LH: Low
Inhibin: 0
E2: 0
What are the levels of FSH, LH, Inhibin, and E2 during Selection
All at medium levels
What are the levels of FSH, LH, Inhibin, and E2 during dominance?
FSH: Low
LH: High
Inhibin: High
E2: High
What cell membranes does LH bind to on an antral follicle?
Theca interna cells
What is LH broken down into at theca interna cell membranes by a protein kinase?
Testosterone
What inner cell type of an antral follicle does testosterone, from the breakdown of LH, bind to?
Granulosa cell
What binds to granulosa cells and causes the b/d of T4 to estrogen?
FSH
The preovulatory LH surge causes an increased blood flow to ____ & _____ which creates _____.
Ovary & dominant follicle
Edema
The preovulatory LH surge causes an increase in ______ which causes the contraction of ovarian smooth muscle and release of lysosomal enzymes.
PGF2a
The increase in PGF2a causes an increase in contraction of ____________ which in turns increases ______ pressure.
Ovarian smooth muscle; Follicular pressure
What are the two causes of increased follicular pressure brought on by the preovulatory LH surge?
Increased ovarian smooth muscle contraction(from increased PGF2a)
Edema(from increased blood flow to ovary & dominant follicle)
The preovulatory LH surge causes a shift from E2 to ____ by the dominant follicle
Progesterone
Progesterone increased by the preovulatory LH surge causes an increase in ______ which helps with follicle wall ______.
Collagenases; weakening
What are the two causes of follicular wall weakening brought on by the preovulatory LH surge?
Release of lysosomal enzymes(brought on by PGF2a)
Increase in Collagenases(brought on by progesterone)
The increased follicular pressure and the weakening of the follicular wall associated with the preovulatory LH surge leads to _____.
Ovulation
The preovulatory LH surge causes gap junction breakdown between _______ & _______.
Granulosa cells, Oocyte
What are the 5 actions brought on by the preovulatory LH surge?
- Increased PGE2
- Increased blood flow to ovary & dominant follicle(also helped by the increase PGE2)
- Increased PGF2a
- Shift from E2 to P4 by dominant follicle
- Gap junction b/d between granulosa cells & oocyte
Females are born with primary oocytes which are arrested in the 1st meiotic division until what?
LH surge
What does a primary oocyte become with an LH surge?
Secondary oocyte with 1st polar body
What brings on the production of a 2nd polar body?
Ovulation–>2nd meiotic division
What is a fertilized secondary oocyte called?
Zygote
What is the only species that ovulates a primary oocyte?
DOGS!!!!!!!
What type of oocyte do most species ovulate?
Secondary oocyte with 1 polar body
