reproductive cycle phases

Question 1

describe the follicular phase of the estrous cycle

Answer 1

proestrus + estrus

• regression of the corpora lutea to ovulation
• about 20% of the cycle
• primary ovarian structure: growing dominant follicle
• primary hormone: estradiol

Question 2

describe the luteal phase of the estrous cycle

Answer 2

metestrus + diestrus
- ovulation until corpora lutea regression
- about 80% of the cycle
- primary ovarian structure: CL
- primary hormone: progesterone

Question 3

the luteal phase is high in __ while the follicular phase is high in __

Answer 3

progesterone, estrodiol

Question 4

during proestrus, __ is decreasing bc of the CL’s destruction and __ is increasing

Answer 4

progesterone, estrogen

Question 5

what is estrus characterized by?

Answer 5

visible behavioral symptoms

Question 6

hypothalamic-pituitary-ovarian -axis during proestrus

Answer 6

the decreasing progesterone allows GnRH pulse frequency to increase which leads to an increase in FSH/LH secretion from the anterior lobe. The FSH/LH act on ovarian follicle to increase estrogen secretion leading to positive feedback increasing GnRH bc then it wants to ovulate. Eventually, estrogen increases and begins to suppress FSH secretion and primarily select for LH secretion

Question 7

hypothalamic-pituitary-ovarian -axis during estrus

Answer 7

• dominant follicle has been selected
• threshold E2 production from DF
• triggers surge center of hypothalamus which increases frequency and amplitude GnRH secretion
• pre-ovulatory LH surge
• Ovulation

Question 8

metestrus

Answer 8

period between ovulation and formation of functional CL where the newly ovulated follicle becomes corpus hemorrhagicum and luteinization begins to make it the CL

decrease estrogen, increase progesterone

Question 9

diestrus is the __ stage of the estrous cycle

Answer 9

longest

Question 10

diestrus has a fully functional __ producing ___ that ends with __

Answer 10

CL, progesterone, luteolysis

Question 11

how is ovulation triggered in spontaneously ovulating species?

Answer 11

ovulation is automatically triggered from estrus

Question 12

how is ovulation triggered in induced ovulating species?

Answer 12

requires mating for ovulation and diestrus to occur

Question 13

progesterone sends __ feedback on GnRH neurons in the hypothalamus

Answer 13

negative

Question 14

luteolysis is when the CL ___ and __ rapidly declines. It is controlled by __ from CL and __ from uterine endometrium

Answer 14

degenerates, progesterone, oxytocin/progesterone, prostaglandin

Question 15

anestrus

Answer 15

condition where female does not exhibit regular estrous cycles

Question 16

how does the bitch’s estrus cycle differ?

Answer 16

estrogen peaks in proestrus before LH peaks in estrus which triggers ovulation

Question 17

in mares, a secondary wave can develop in diestrus and give rise to a follicle that may or may not __. If it does, then __ can result

Answer 17

ovulate, twins

Question 18

in the mare, the LH surge peaks __ovulation while estradiol is __ at ovulation

Answer 18

after, highest

Question 19

T/F: camelids display overt signs of estrus

Answer 19

F

Question 20

T/F: camelids are induced ovulators and are usually receptive unless there is a CL present

Answer 20

T

Question 21

Cows estrous cycle is ___ days and estrus is __lasting about 15 hours

Answer 21

21, short

Question 22

Ewes/Does are __ day breeders and ewes have a __ estrous cycle than does

Answer 22

short, shorter

Question 23

estrus in swine is __ days while diestrus is __

Answer 23

1-3, 16-18

Question 24

how can you test if a sow is in estrus?

Answer 24

they may be mounting or exhibiting lordosis or you can do the back pressure test

Question 25

ovulation happens towards the __of estrus in swine

Answer 25

end

Question 26

ovulation happens towards the __ of estrus in canines

Answer 26

beginning