Chapter 8 Flashcards
What is the driving force for initiation of the follicular phase?
luteolysis
What does the follicular phase consist of?
proestrus and estrus
Where are LH and FSH released from?
anterior pituitary lobe
What four events take place in follicular phase?
1) Gonadotropin release
2) follicular preparation for ovulation
3) sexual receptivity (estrus)
4) ovulation
What is the follicular phase goverend by?
hypothalamus, anterior lobe, ovary (ovarian estrogen secretion)
What is the surge center also known as?
preovulatory center
What is the positive stimulus received by the surge center?
where it releases basal leaves of GnRh until estradiol threshold concentration is reached
What makes up the tonic GnRh center? (hypothalamic nuclei)
ventro-medial and arcuate nucleus
What makes up the surge center (hypothalamic nuclei)?
preoptic nucleus, anterior hypothalamic area, and suprechiasmatic nucleus
What causes GnRH secretion directly caused by?
depolarization (action potentials) from cells bodies of nuerosecretory cells
What is the release of GnRH in the tonic center compared to?
water faucets being gradually turned on (basal secretion)
How often does tonic secretion of GnRH occur?
entire estrous cycle
How often does the preovulatory surge of GnRH happen during estrous?
once
What can the preovulatory surge of GnRH be compared to?
a faucet fully open for a short period of time
What type of feedback is the surge center sensitive to?
positive
How often do small GnRH episodes in the tonic center happen in the follicular and luteal phase?
Follicular: every 1.5 - 2.0 hours
Luteal: every 4 to 8 hours
How low is neural secretion of GnRH in tonic center? What does this cause?
5 pg/ml and low LH secretion
What type of feedback does low estradiol concentrations cause to the preovulatory center?
negative
What does low estrodiol concentrations cause?
low firing of GnRH nuerons
What type of feedback does high estradiol concentration cause to the preovulatory center?
positive
When do the follicles begin to produce more and more estradiol?
proestrus
When is the preovulatory center turned on?
when estradiol reaches threshold concentration
What is essential for initiating the follicular phase of estrous?
GnRH elevating
What is the surge center ultimately responsible for?
secretion of large quantitites of GnRH thus causing the surge of LH that causes ovulation
What is the surge center ultimately responsible for?
secretion of large quantities of GnRH thus causing the surge of LH that causes ovulation
Follicular growth and degeneration is known as what?
follicular dynamics
What do the dynamics of the antral follicles consist of?
recruitment (emergence/growing), selection (the growing follicles that have not undergone atresia), dominance, atresia
Which animals have a cohort (group) of follicles become dominant?
gos, cats, pig,
What animals have only a single follicle that becomes dominant?
cattle, mares, and women
What do growing/antral follicles secrete?
estradiol and inhibin
What does monotocous species mean?
giving birth to a single offspring
What does polytocous species mean?
litter bearers
What effect do large preovulatory follices have on other follicles?
inhibitory effect (less blood supply to some follicles) and less FSH
How does atresia occur?
continuously throughout folliculogenesis`
What percent of follicles undergo atresia?
90%
Atretic antral follicles are in what?
atresia (degenerative)