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Repro > Reproductive Cyclicity in the Female > Flashcards

Reproductive Cyclicity in the Female Flashcards

1
Q

are estrus and estrous synonymous?

A

no, estrus is a noun and estrous is an adjective (the cycle)

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2
Q

are estrus and heat synonymous?

A

yes

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3
Q

what is anestrus?

A

when the female is not having repeated estrous cycles, usually normal causes

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4
Q

what is polyestrus?

A

repeated cycles at regular intervals throughout the year

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5
Q

what is seasonally polyestrus?

A

estrous cycles at regular intervals that depend on season, specifically day length

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6
Q

when do short day seasonally polyestrus animals cycle?

A

in the fall in the northern hemisphere

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7
Q

when do long day seasonally polyestrus animal cycle?

A

spring and summer in the northern hemisphere

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8
Q

are seasonally polyestrus cycles more or less regulated as you move closer to the equator?

A

less regulated

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9
Q

give the 3 types of cyclicity

A
  1. polyestrus
  2. seasonally polyestrus
  3. monoestrus
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10
Q

define monoestrus

A

1-2 cycles per year, lots of species variation but cycles can average 6-8 months long

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11
Q

how long is the cow reproductive cycle?

A

21 days long

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12
Q

why type of cyclicity do cows have?

A

polyestrus

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13
Q

how long is estrus for cows?

A

12-18 hours

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14
Q

when do cows ovulate?

A

11 hours AFTER estrus

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15
Q

how long is pregnancy for cows?

A

282 days

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16
Q

what type of cyclicity do ewes/goats have?

A

seasonal short day breeders (in the fall)

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17
Q

how long is the ewe/goat reproductive cycle?

A

17 days

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18
Q

how long is estrus for ewe/goat?

A

24-36 hours

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19
Q

when do ewes/goats ovulate?

A

near end of estrus

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20
Q

how long is ewe/goat pregnancy?

A

148 days

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21
Q

what type of cyclicity do sows have?

A

polyestrus

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22
Q

how long is the sow repro cycle?

A

21 days

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23
Q

when do sows ovulate?

A

35-45 hours after start of estrus

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24
Q

how long is sow estrus?

A

48-72 hours

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25
Q

how long is sow pregnancy?

A

115 days

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26
Q

what type of cyclicity do mares have?

A

seasonally polyestrus, long day (spring) breeders

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27
Q

how long is estrus for mares?

A

5-7 days

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28
Q

when do mares ovulate?

A

days 3-6 of estrus, 1-2 days before the end of estrus

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29
Q

how long is pregnancy for mares?

A

335-340 days

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30
Q

how long is the estrous cycle of a bitch?

A

6 months

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31
Q

how long is estrus for a bitch?

A

9 days

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32
Q

when do bitches ovulate?

A

4-24 days after start of estrus

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33
Q

how long is a bitch’s pregnancy?

A

63 days

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34
Q

how long is the estrous cycle of a queen?

A

17 days

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35
Q

how long is estrus for a queen?

A

9 days

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36
Q

when do queens ovulate?

A

they are induced ovulators

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37
Q

how long is a queen’s pregnancy?

A

63 days

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38
Q

when referring to cycle type, what does spontaneous mean?

A

happens regardless of mating

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39
Q

when referring to cycle type, what does induced mean?

A

requires mating in order to occur

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40
Q

are phases and stages of the estrous cycle the same?

A

NOOOOO

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41
Q

list the 2 PHASES of the estrous cycle

A
  1. follicular phase

2. luteal phase

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42
Q

describe the follicular phase of the estrous cycle, incluing what dominates the ovarian structure and what the dominant hormone is

A

follicles dominate ovarian structure, dominant hormone is estrogen

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43
Q

describe when the follicular phase of the estrous cycle occurs

A

from regression of the previous CL to approximately ovulation

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44
Q

in cattle, how much of the estrous cycle is taken up by the follicular phase?

A

about 20%

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45
Q

describe the luteal phase of the estrous cycle, including what dominates the ovarian structure and what the dominant hormone is

A

corpora lutea dominant ovarian structure, progesterone is dominant hormone

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46
Q

when does the luteal phase of the estrous cycle occur?

A

from ovulation until CL regression (if no baby)

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47
Q

how long of the cattle estrous cycle is take up by the luteal phase?

A

about 80%

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48
Q

how many stages are in the estrous cycle?

A

4

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49
Q

which two stages of the estrous cycle occur during the follicular phase?

A

proestrus and estrus

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50
Q

which two stages of the estrous cycle occur during the luteal phase?

A

metestrus and diestrus

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51
Q

describe proestrus, including length

A

the stage that immediately precedes estrus (heat), 2-5 days long depending on the species

52
Q

describe what is happening in terms of steroid hormones during proestrus (3)

A
  1. stage begins when P4 levels start to decline due to leutolysis of previous CL
  2. major endocrine transition from P4 dominance to E2 dominance
  3. net increase in E2
53
Q

describe what is happening in the ovary during proestrus (3)

A
  1. preovulatory follicle is enlarging
  2. antrum is getting larger in diameter
  3. granulosa cells producing more and more E2
54
Q

describe what is happening in the repro tract during proestrus (2)

A
  1. endometrial gland growth in uterus

2. more cilia in oviduct

55
Q

what percentage of the reproductive cycle is taken up by the follicular phase? in cattle

A

about 20%

56
Q

what dominates the ovrian structure in the follicular phase?

A

ovarian follicles

57
Q

what is the dominant hormone during the follicular phase?

A

estrogen, E2

58
Q

what events mark the beginning and end of the follicular phase?

A

goes from regression of previous CL until approximately ovulation

59
Q

what percentage of the repro cycle is taken up by the luteal phase in cattle?

A

about 80%

60
Q

what dominates the ovarian structure during the luteal phase?

A

corpora lutea

61
Q

what is the dominant hormone during the luteal phase?

A

progesterone

62
Q

what events mark the beginning and end of the luteal phase?

A

from ovulation until CL regression if animal is not pregnant

63
Q

broadly define estrus (2)

A
  1. behavioral change in female to be more receptive to mating
  2. standing heat
64
Q

describe what is happening in terms of steroid hormones during estrus (1)

A

E2 decreases during this stage

65
Q

describe what is happening in terms of gonadotropins during estrus (1)

A

LH surge due to high E2 levels from proestrus

66
Q

describe what is happening to the ovary during estrus (1)

A

24-48 hours after LH surge, pre-ovulatory follicle will ovulate

67
Q

when do cattle ovulate?

A

during metestrus

68
Q

describe what is happening with the repro tract during estrus (2)

A
  1. uterine motility is high due to muscle contractions, which contract toward oviduct for optimal sperm transport
  2. high levels of cervical mucus, especially in mares and ruminants like cattle
69
Q

what is metestrus?

A

the time between ovulation and functional CL formation

70
Q

describe what is happening in terms of steroid hormones during metestrus (1)

A

E2 and P4 are low

71
Q

describe what is happening in terms of gonadotropins during metestrus (1)

A

increase in FSH will initiate new waves of follicles, due to increased negative feedback from E2 and inhibin

72
Q

describe what is happening in the ovary during metestrus in CATTLE

A

ovulation in CATTLE only

73
Q

describe what is happening in the repro tract during metestrus (2 and then 1 just for cattle)

A
  1. decreased uterine contractions
  2. endometrial gland growth and secretions, endometrial glands are becoming coiled in appearance
  3. may see bleeding in cattle, diapadesis
74
Q

what is diapadesis?

A

leaky vasculature

75
Q

what is diestrus?

A

the longest stage of the cycle

76
Q

when does diestrus begin?

A

at P4 production

77
Q

describe what is happening in terms of steroid hormones during diestrus?

A

HIGH P4

78
Q

describe what is happening in terms of gonadotropins during diestrus

A

FSH increases and decreases, creating new follicular waves

79
Q

describe what is happening in the repro tract during diestrus

A
  1. initially uterine contractions and secretions are very high
  2. as diestrus progresses, uterine contractions and secretions will decrease
  3. P4 quiets the uterus, decreasing uterine contractions
  4. if animal is NOT pregnant, uterus will produce PGF2a, which lyses CL and animal will go back into proestrus
80
Q

how long is the menstrual cycle?

A

28 days

81
Q

what is day 0 of the menstrual cycle?

A

the first day of menses (bleeding)

82
Q

on what day of the menstrual cycle does ovulation occur?

A

day 14

83
Q

in the menstrual cycle, how long do follicular and luteal phases last?

A

SAME amount of time, 14 days each

84
Q

how long, on average, does proestrus last in bitches? what is the range?

A

7-10 days, can range from 4-20 days

85
Q

how long on average does estrus last in bitches? what is the range?

A

9 days, can range from 3-21 days

86
Q

describe estrus in bitches (5)

A
  1. E2 decline, LH surge
  2. ovulation towards end of estrus
  3. female will allow mating
  4. maximum keratinization
  5. P4 increases prior to ovulation
87
Q

describe proestrus in bitches (4)

A
  1. E2 increasing, peaks at end
  2. swelling of vulva
  3. vaginal, bloody discharge (diapadesis)
  4. keratinization increases in vaginal epithelium for protection, can be used to determine appropriate breeding times
88
Q

describe metestrus in bitches

A

absent

89
Q

how long does diestrus last in bitches?

A

70-80 days, makes up entire luteal phase

90
Q

when does diestrus begin in bitches?

A

about 6 days post ovulation

91
Q

describe what is happening in terms of steroid hormones in bitches during diestrus

A
  1. P4 begins very high and then starts to decline

2. if bitch is not pregnant, P4 drops and a pseudopregnancy can be observed

92
Q

when does diestrus end for bitches in terms of steroid hormones?

A

stage ends when P4 drops to less than 1ng/mL, usually prior to whelping if bitch is pregnant

93
Q

describe what is happening in the repro tract during diestrus for bitches

A

uterus is not active in CL regression, meaning it does not release PGF2a to lyse the CL, so the CL will last entire length of a pregnanct, even if bitch is not pregnant (pseudopregnancy)

94
Q

how long is anestrus on average for bitches? what controls the extreme variation?

A

4-6 months, highly variable; genetics and environment control length of this stage

95
Q

when referring to a queen, what is interestrus?

A

diestrus + anestrus

96
Q

what happens behaviorally during estrus in a queen?

A

they will vocalize, assume lordosis position, restless

97
Q

describe the lordosis position in a queen

A

arched back

98
Q

if a queen is not mated, what stage occurs?

A

post estrus

99
Q

what happens in post estrus in queens? (3)

A
  1. no ovulation
  2. E2 declines, P4 also low
  3. new follicular wave begins
100
Q

if a queen is mated, what follows? (4)

A
  1. LH surge is induced
  2. ovulations of multiple follicles
  3. CLs cause high P4
  4. uterus will not release PGF2a, so a pseudopregnancy can occur if mating was unsuccessful and not pregnant
101
Q

if a queen is mated but not pregnant, when will P4 return back to normal levels?

A

after approximately the same number of days as gestation

102
Q

what percentage of queens will ovulate after breeding?

A

50%

103
Q

when will peak LH surge ovulations occur in terms of queens and number of matings?

A

peak LH ovulations will occur with 8-12 matings of short duration, as queens are induced ovulators

104
Q

list 3 normal causes of anestrus

A
  1. pregnancy
  2. season
  3. presence of offspring
105
Q

list 3 abnormal causes of anestrus

A
  1. inadequate nutrition
  2. stress
  3. pathology
106
Q

List the 4 types of anestrus

A
  1. gestational anestrus
  2. seasonal anestrus
  3. lactational anestrus
  4. nutritional anestrus
107
Q

what causes gestational anestrus?

A

progesterone from pregnancy exerts negative feedback on the hypothalamus

108
Q

why does gestational anestrus continue after pregnancy?

A

due to the long progesterone exposure during pregnancy, the hypothalamus lacks estradiol positive feedback

109
Q

what is the reason for gestational anestrus continuing for a while after pregnancy?

A

allows for uterine involution

110
Q

what does the sheep seasonal anestrus cycle line up with?

A

when forage is available and of good quality

111
Q

describe the 5 steps of day length affecting cyclicity of a sheep (short day breeders) during long day seasons

A
  1. increased light will act on receptors in retina
  2. receptors communicate with pineal gland; cause a decrease in melatonin production
  3. decreased melatonin signal to hypothalamus to decrease GnRH secretion
  4. this decreases FSH and LH levels
  5. this decreases gonadal stimulation to pause cyclicity
112
Q

describe the 5 steps of day length affecting cyclicity of a horse (long day breeder) during long day seasons

A
  1. increased light will act on receptors in retina
  2. receptors communicate with pineal gland; cause a decrease in melatonin production
  3. decreased melatonin signals to hypothalamus to INCREASE GnRH secretion
  4. this increases FSH and LH levels
  5. this increases gonadal stimulation to resume cyclicity
113
Q

what is silent ovulation?

A

ovulation without behavioral heat

114
Q

what does the brain need in order to express estrus in response to estrogen?

A

it must first be primed with progesterone

115
Q

when is silent ovulation common?

A

in first ovulation after a period of anestrus

116
Q

list a describe the 2 types of E2 receptors in the hypothalamus

A
  1. receptors for surge: don’t need P4 to work

2. receptors for behavior: have to have been exposed to P4 to work

117
Q

what animal has a very high degree of lactational anestrus?

A

pigs

118
Q

describe the effect of suckling on LH secretion

A

as suckling decreases, LH secretions increase to resume cyclicity

119
Q

list the 3 general factors that relate to lactational anestrus

A
  1. suckling
  2. other offspring factors
  3. prolactin
120
Q

what are the three offspring factors that affect lactational anestrus?

A
  1. visual encounter
  2. olfactory encounter
  3. auditory encounter
121
Q

what can excess prolactin do to humans?

A

lead to infertility

122
Q

what happens to males (fathers) when offspring are born in response to cues and why?

A

excess prolactin production, leads to paternal bonding

123
Q

what is the right window to avoid nutritional anestrus?

A

right between too low and too high body fat

124
Q

what causes body fat to be too low and what is the result?

A

nutritional deficit leads to nutritional anestrus

125
Q

what happens when body fat is too high and what is the result?

A

disregulation of metabolism, nutritional anestrus

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