Follicular Physiology, Ovulation, Luteinization, Luteolysis Flashcards
What process of follicular dynamics is characterized by high FSH, low LH, no inhibin, and no E2?

recruitment

T/F: The sow ovulates a primary oocyte
False
The dog ovulates a primary oocyte

What is the dominant hormone during the luteal phase?
progesterone

Ovulation typically occurs during estrus, except in __________
cows
Usually a 12-hour period. If you see them in heat, you breed them 12 hours later
Describe the hormonal pre-ovulatory events that occur, starting with a decrease in progesterone (due to luteolysis):
- Decrease in P4 due to luteolysis
- Release of negative feedback of P4 at hypothalamus, which increases GnRH, increasing FSH and LH
-
Developing follicle increases estrogen and inhibin production
- Estrogen sends positive feedback to the surge center, resulting in even more release of GnRH
- Simultaneously, inhibin and estrogen send negative feedback to FSH in the anterior pituitary, resulting in a huge amount of LH
- Preovulatory LH surge
- Boom.

Which of the following is seasonally polyestrus:
- Horse
- Cow
- Sow
- Dog
Horse
T/F: Progesterone induces luteolysis
False

Degeneration of antral follicles is termed:
atresia
What are the 3 main events that occur during the luteal phase?
- Luteinization of follicular cells to luteal cells
- Growth/development of CL ∴ production of P4
- Luteolysis

What is the dominant hormone during the follicular phase of the estrous cycle?
Estrogen

The bitch ovulates _____ days after LH surge
2-3 days

What are the four major events during the follicular phase of the estrous cycle?
- Rising levels of gonadotropin release from anterior pituitary
- Follicular growth/prep for ovulation
- Sexual receptivity
- Ovulation

What stages of the estrous cycle are involved in the follicular phase?
proestrus and estrus
Pathways to luteolysis vary by species. Luteolysis occurs via only a systemic pathway in __________
mares
How does PGF2a get from the uterus to the ovary? Prostaglandin PGF2a from the uterus is transported to the ipsilateral ovary through a vascular countercurrent exchange mechanism. The countercurrent diffusion system is present in the cow, sow, and ewe, but not in the mare.
The key player in luteolysis is:
PGF2a
Generally uterine endometrium is the source of PGF2a in domestic animals
Which stages of the estrous cycle are involved in the luteal phase?
metestrus and diestrus

Luteinization is the transformation of the theca interna and granulosa cells of the follicle to luteal cells producing P4. Granulosa cells become __________ and theca interna cells become __________
Luteinization is the transformation of the theca interna and granulosa cells of the follicle to luteal cells producing P4. Granulosa cells become large luteal cells and theca interna cells become small luteal cells

Positive feedback from what hormone causes GnRH release from the surge center?
- Progesterone
- Estrogen
- FSH
- LH
Estrogen
Which of the following is not an important event during the follicular phase of the ovary?
- Elevated GnRH release from pituitary
- Preparation for ovulation
- Sexual receptivity
- LH surge
- Progesterone secretion
Progesterone secretion
What process of follicular dynamics is characterized by low FSH, high LH, and high inhibin?
dominance

___________ refers to decomposition of the corpus luteum
Luteolysis refers to decomposition of the corpus luteum.
It occurs during a 1-3 day period at the end of the luteal phase. If luteolysis does not occur, the animal will remain in a sustained luteal phase because progesterone inhibits gonadotropin secretion
T/F: Progesterone blocks the preovulatory LH surge
True

T/F: Progesterone increases basal GnRH amplitude and frequency
False

T/F: Elevated GnRH is essential for initiating the follicular phase of the estrous cycle
True

__________ ovulators require stimulation of the vagina and/or cervix for ovulation to occur
induced ovulators
- Rabbits, minks, ferrets, giant fruit bats, cats, the 13 –lined ground squirrel, Sumatran rhinos
- Camelids appear to also require a substance in seminal plasma for ovulation
- Cats have a 50% of ovulation if mated once
- Lions have been reported to mate more than 100 times during the 2-4 day estrus cycle.
During the follicular phase, the tonic center of the hypothalamus releases small pulses of GnRH that stimulate release of __________ from the anterior pituitary
FSH and LH
This causes growth and development of follicles on the ovary. The follicles produce estrogen.
During the recruitment phase of follicular development, which hormone is dominant?
- FSH
- LH
- Inhibin
- Estrogen
FSH
What physiologic effect does progesterone have on uterine tone?
causes relaxation of the uterus

The surge center of the hypothalamus responds in a positive-feedback-fashion to increasing levels of __________ in absence of __________ to release large quantities of GnRH
The surge center of the hypothalamus responds in a positive-feedback-fashion to increasing levels of estrogen (produced by follicle) in absence of progesterone to release large quantities of GnRH
- This causes release of LH and leads to ovulation*
- **The surge center is “turned on” once estrogen reaches threshold level***
The cells of the theca interna contain receptors for LH. Thecal cells produce __________ that diffuses into the granulosal cells that contain FSH receptors.
The cells of the theca interna contain receptors for LH. Thecal cells produce testosterone that diffuses into the granulosal cells that contain FSH receptors.
Binding of FSH to the granulosal cell receptors causes the synthesis of enzymes that are responsible for the conversion of testosterone to estradiol
