Ovulation, Luteinization, Luteolysis

Question 1

Ovulation is dependent on what?

Answer 1

LH surge

Question 2

How long does the LH surge last in most species? What is the exception to this rule?

Answer 2

24 hrs

Mares(3-5 day elevation)

Question 3

Most species ovulate during which phase of the estrous cycle? Which species is the exception?

Answer 3

Estrus

Cow

Question 4

How long after the LH surge do dogs ovulate?

Answer 4

2-3 days

Question 5

An ovulated follicle collapses and becomes a ______.

Answer 5

Corpus hemorrhagicum

Question 6

What type of oocyte do most species ovulate? What is the exception?

Answer 6

Secondary oocyte

Dogs-primary oocyte

Question 7

What two parts of the estrous cycle take place in the luteal phase?

Answer 7

Metestrus & Diestrus

Question 8

What are the 3 main events of the luteal phase?

Answer 8

1. Luteinization of follicular cells to luteal cells
2. Growth/development of CL–>production of P4
3. Luteolysis

Question 9

During which part of the estrous cycle does CL formation(luteinization) take place?

Answer 9

Metestrus

Question 10

The basement membrane between the granulosal & theca interna cells of a preovulatory follicle begin to breakdown as what approaches?

Answer 10

Ovulation

Question 11

What cells of a CL produce P4 until luteolysis?

Answer 11

Luteal cells

Question 12

When do luteal cells of a CL stop producing P4?

Answer 12

Luteolysis

Question 13

Transforming of the theca interna and granulosa cells of the follicle to luteal cells producing P4 is called what?

Answer 13

Luteinization

Question 14

What size luteal cells do granulosa vs. theca interna cells become?

Answer 14

Granulosa–>Large luteal cells
Gran is large

Theca interna–>Small luteal cells
Must be small to fit Interna-lly

Question 15

What type of feedback does P4 have on the hypothalamus?

Answer 15

Negative: stops GnRH from being released

Question 16

What effects does P4 have on the uterus?

Answer 16

Decreases myometrial tone(ie. relaxes the uterus)
EXCEPT in MARES!

Increases “uterine milk”(ie. secretions)

Question 17

What hormones do luteal cells produce?

Answer 17

P4
Oxytocin
Relaxin

Question 18

P4 reduces myometrial tone except in which species?

Answer 18

Mares

Question 19

How does P4 effect the mammary glands?

Answer 19

Promotes alveolar development

Question 20

When does a cow ovulate?

Answer 20

Metestrus

Question 21

Which days of the cycle do Metestrus & Diestrus take place? Which species is the exception?

Answer 21

Metestrus: 1-5
Diestrus: 5-17

Pigs
Metestrus: 1-10
Diestrus: 10-17

Question 22

Which hormone causes luteolysis?

Answer 22

PGF2a

Question 23

PGF2a causes _______ which releases the negative feedback of ____ on the hypothalamus & anterior pituitary.

Answer 23

Luteolysis, P4

Question 24

What does PGF2a come from?

Answer 24

Uterine endometrium

Question 25

Which species have a local countercurrent exchange of PGF2a from ipsilateral uterine vein & ovarian artery?

Answer 25

Ruminants

Question 26

Which species has a systemic pathway of luteolysis?

Answer 26

Mares

Question 27

Which species has a combination of a systemic and a local countercurrent exhange of PGF2a for luteolysis?

Answer 27

Pigs

Question 28

What can be given to lyse a CL?

Answer 28

Luteolyse

Question 29

How are horses vs. cows affected by Luteolyse?

Answer 29

Horses get colicky if given too much because it goes systemically while a cow won’t show any signs….therefore give horses a lower dose

Question 30

When do oxytocin receptors appear in the endometrium?

Answer 30

Late luteal phase

Question 31

What effect does oxytocin have on PGF2a?

Answer 31

Stimulates a pulse release

Question 32

What effect does PGF2a have on Oxytocin?

Answer 32

Stimulates more oxytocin