Follicular Physiology, Ovulation, Luteinization, Luteolysis Flashcards Preview

RUSVM Theriogenology > Follicular Physiology, Ovulation, Luteinization, Luteolysis > Flashcards

Flashcards in Follicular Physiology, Ovulation, Luteinization, Luteolysis Deck (30):
1

What process of follicular dynamics is characterized by high FSH, low LH, no inhibin, and no E2?

recruitment

2

 T/F: The sow ovulates a primary oocyte

False

The dog ovulates a primary oocyte​

3

What is the dominant hormone during the luteal phase?

progesterone

4

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

5

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.

6

Which of the following is seasonally polyestrus:

  • Horse
  • Cow
  • Sow
  • Dog

Horse

7

T/F: Progesterone induces luteolysis

False

8

Degeneration of antral follicles is termed:

atresia

9

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

10

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

Estrogen

11

The bitch ovulates _____ days after LH surge

2-3 days

12

 What are the four major events during the follicular phase of the estrous cycle?

  1. Rising levels of gonadotropin release from anterior pituitary
  2. Follicular growth/prep for ovulation
  3. Sexual receptivity
  4. Ovulation

13

What stages of the estrous cycle are involved in the follicular phase?

proestrus and estrus

14

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.

15

The key player in luteolysis is:

PGF2a

Generally uterine endometrium is the source of PGF2a in domestic animals

16

Which stages of the estrous cycle are involved in the luteal phase?

metestrus and diestrus

17

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

18

Positive feedback from what hormone causes GnRH release from the surge center?

  • Progesterone
  • Estrogen
  • FSH
  • LH

Estrogen

19

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​

20

What process of follicular dynamics is characterized by low FSH, high LH, and high inhibin?

dominance

21

___________ 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

22

T/F: Progesterone blocks the preovulatory LH surge

True

23

T/F: Progesterone increases basal GnRH amplitude and frequency

False

24

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

True

25

__________ 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.

26

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.

27

During the recruitment phase of follicular development, which hormone is dominant?

  • FSH
  • LH
  • Inhibin
  • Estrogen

FSH

28

What physiologic effect does progesterone have on uterine tone?

causes relaxation of the uterus

29

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**

30

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