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Histology Pt. 2 > Bovine and Small Ruminant Repro > Flashcards

Bovine and Small Ruminant Repro Flashcards

1
Q

What type of breeders are bovine?

A

polyestrous

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2
Q

What type of ovulators are bovine?

A

monovulatory - one egg per estrus phase

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3
Q

After puberty, what is the cyclicity like in the bovine for the rest of its life?

A

routine normal cyclicity that continues throughout its life unless inhibited by disease or pregnancy

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4
Q

What is the length of the estrous cycle in the bovine?

A

21 days on average (range: 17-24 days)

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5
Q

What are the two centers in the hypothalamus for GnRH release?

A

surge center and tonic center

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6
Q

How does the surge center work in releasing GnRH?

A

it is what dictates the huge surge of GnRH that causes ovulation

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7
Q

How does the tonic center work in releasing GnRH?

A

it allows for a constant release of GnRH no matter where we are in the estrous cycle

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8
Q

When is the tonic center stimulated to begin GnRH release?

A

during puberty

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9
Q

What two hormones are released from the anterior pituitary that are involved in the estrous cycle?

A

FSH and LH

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10
Q

What is the role of FSH?

A

it is needed for the recruitment of follicles and the growth of follicles

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11
Q

What is the role of LH?

A

final maturation of the ovary for ovulation

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12
Q

What two cells are important in estrous?

A

granulosa cells and theca cells

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13
Q

What do granulosa cells and theca cells produce?

A

estrogen

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14
Q

How many folicular waves are there typically in a bovine estrous cycle?

A

two to three

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15
Q

What is progesterones role in the estrous cycle?

A

it is the gate keeper; it dictates what happens on the ovary, if present the ovary cannot ovulate

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16
Q

What decreases the level of progesterone in the estrous cycle?

A

natural luteolysis

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17
Q

If the estrous cycle is 18-19 days long, how many follicular waves will the bovine most likely have?

A

two

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18
Q

If the estrous cycle is 24 days long, how many folliclular waves will the bovine have?

A

three

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19
Q

During recruitment, what are hormone levels of FSH, LH, and estrogen like?

A

FSH is high for follicular growth, LH is limited because it is reserved for ovulation, and there are insignificant levels of recruitment

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20
Q

During selection, what are hormone levels of FSH, LH, and estrogen like?

A

there is not much FSH because follicles are growing, increased LG and more estrogen is being produced than in recruitment

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21
Q

What is inhibins role in selection?

A

it is involved to make sure that only one follicle is released during ovulation

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22
Q

In selection, what is inhibin released from?

A

the dominant follicle to suppress its cohorts

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23
Q

What are the hromone levels like during dominance?

A

inhibin levels keep increasing, there is an LH surge for ovulation, and increased estrogen

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24
Q

What are the two types of inhibin and what are their roles?

A

alpha and beta, alpha allows for litters and multiple dominant follicles, beta only allows for one dominant follicle

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25
Q

How and when is estrogen involved in negative feedback?

A

for the majority of the estrous cycle, if estrogen is produced/present and progesterone levels are high (present) then the system is told that no more estrogen is needed so it is not produced

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26
Q

How and when is estrogen involved in positive feedback?

A

when progesterone is gone during the estrus phase, estrogen levels increase its production because it is needed

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27
Q

What are the two phases of the estrous cycle?

A

follicular and luteal phase

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28
Q

What are the two sub phases of the follicular phase?

A

proestrous and estrus

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29
Q

What are the two sub phases of the luteal phase?

A

metestrus and diestrus

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30
Q

What is the follicular phase?

A

the period from regression of the corpus lutea to ovulation

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31
Q

What primary ovarian structures are involved in the follicular phase?

A

growing dominant follicle and regressing CL

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32
Q

What primary hormone is involved in the follicular phase?

A

estrogen

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33
Q

When does proestrus occur?

A

after diestrus or anestrous immediately preceeding estrus when progesterone declines from resulting luteolysis

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34
Q

How long is proestrus usually?

A

between 2-5 days

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35
Q

What transition period occurs during proestrus?

A

the transition between progesterone dominance to estrogen dominance

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36
Q

What is estrus characterized as?

A

a period of sexual receptivity

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37
Q

What are some physical signs that a bovine is in estrus?

A

increased locomotion, vocal expression, nervousness, and mounting

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38
Q

How long does estrus typically last in the bovine?

A

16 hours

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39
Q

When do bovine typically ovulate?

A

12-16 hours post standing estrus

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40
Q

What is the time from standing estrous to ovulation?

A

typically 30 hours

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41
Q

If a cow is in standing estrus in the morning, when would we typically inseminate?

A

in the PM

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42
Q

If a cow is in standing estrus in the evening when would we typically inseminate?

A

in the morning

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43
Q

What is released from the anterior pituitary during the follicular phase?

A

everything

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44
Q

Why is FSH released in the follicular phase?

A

for follicle stimulation

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45
Q

What part of the estrous cycle has the highest estrogen period?

A

estrus

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46
Q

What does blood on the tail indicate?

A

that a cow probably just went past her heat a couple of days prior

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47
Q

What causes blood on the tail?

A

estrogen will cause blood vessels to burst

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48
Q

What are some methods, aside from physical signs, that can be used to help determine if a cow is in standing estrus?

A

paint on the tails (if it rubs off, she has been mounted) and a pressure detector (a lot of pressure will change the color of the detector)

49
Q

What is the longest phase of the estrous cycle?

A

the luteal phase

50
Q

When does the luteal phase occur?

A

it is the period from ovulation of the dominant follicle to the regressionof the corpus lutea

51
Q

What is the primary ovarian structure during the luteal phase?

A

the corpus luteum

52
Q

What is the primary hormone of the luteal phase?

A

progesterone

53
Q

What happens to follicles during the luteal phase?

A

they are constantly growing and regressing but they do not produce enough estrogen to proceed into the follicular phase

54
Q

When does metestrus occur?

A

it is the period between ovulation and formation of the CL

55
Q

What are hormone levels like early on in metestrus?

A

progesterone and estrogen are low

56
Q

What do granulosa and theca cells turn into in the metestrus phase?

A

luteal cells

57
Q

Is diestrus or metestrus longer?

A

diestrus

58
Q

What happens in diestrus?

A

the corpus luteum is fully functional and production of progesterone is high

59
Q

When does diestrus end?

A

at luteolysis or termination of pregnancy; by the activation of prostaglandin release

60
Q

What is the precursor for all androgens, progesterone, and estrogens?

A

cholesterol

61
Q

When will the highest level of progesterone occur in the estrous cycle?

A

at approximately day 11

62
Q

Can you palpate a cow to tell what day she is in her estrous cycle?

A

no

63
Q

If a follicle gets to 8mm what will it become?

A

the dominant follicle - will grow to 16-18 mm follicle

64
Q

What is anestrus?

A

the condition where a heifer/cow has not been seen in estrus

65
Q

What can cause anestrus?

A

delayed puberty and post-partum anestrous causes

66
Q

What can cause post-partum anestrous?

A

too short time since calving, negative energy balance, health issues, or lactational issues

67
Q

What happens to hormones in postpartum anestrus?

A

elimination of progesterone and estrogens at parturition and relatively long suppression of FSH and LH during late gestation

68
Q

What is the voluntary wait period?

A

the period of time where dairies woll not breed an animal post partum (55-75 days)

69
Q

When signifies resumption of cycle?

A

it is the first FSH increase within 3-5 days postpartum, however, it typically does not have other components to finish the cycle

70
Q

When do dairy cattle typically resume their cycle?

A

15-45 days postpartum

71
Q

When do beef cattle typically resume their cycle?

A

30-130 days postpartum

72
Q

Why do dairy cattle resume cyclicity before beef cattle?

A

most likely because the calf is removed in order to prevent diseases

73
Q

Why would a calf have an effect on cyclicity in a cow?

A

it inhibits GnRH and LH frequency and surge; it establishes the negative feedback of estrogen on the hypothalamus

74
Q

How can lactation inhibit signs of estrus?

A

prolactin will suppress GnRH therefore suppress the LH surge

75
Q

What is the purpose of exogenous drugs used in reproduction?

A

treatment of disease processes, control the estrous cycle, and alter the estrous cycle

76
Q

What is MRP?

A

maternal recognition of pregnancy

77
Q

When must MRP occur?

A

prior to luteolysis

78
Q

What hormone must be present for MRP and why?

A

progesterone to allow changes in the endometrium

79
Q

What molecule signals to the cow that she is pregnant?

A

interferon-T

80
Q

What is interferon-T produced by and what is its specific function?

A

it is produced by the trophoblast cells in the embryo and blocks the release of prostaglandin from the endometrium by blocking oxytocin receptors

81
Q

What cells make up the placenta?

A

trophoblasts

82
Q

When does attachment of the embryo start and when is it completed?

A

it starts at day 20 and is completed by day 40

83
Q

What type of connection do cattle have with their embryo (placentation) and how many layers between the two?

A

syndesmochorial; 6 layers

84
Q

What type of placenta do cattle have?

A

cotyledonary: cotyledon from the fetus and caruncle from the mother

85
Q

What are the three parts of the ruminant placenta?

A

amnion, allantois, chorion

86
Q

What is the function of the amnion?

A

it provides nutrients to the fetus

87
Q

What is the function of the chorion?

A

it attaches to the endometrium of the maternal side

88
Q

How can pregnancy be diagnosed?

A

rectal palpation, ultrasound, and blood tests (least effective)

89
Q

What is the average gestational length of the bovine?

A

283 days

90
Q

What dictates the length of gestation?

A

fetus

91
Q

What hormone is needed throughout gestation?

A

progesterone

92
Q

What is the primary source of progesterone for the first 5 months?

A

CL

93
Q

What is the primary source of progesterone 6-8 months into pregnancy?

A

the placenta

94
Q

What takes over progesterone production in the last month of gestation?

A

CL

95
Q

How many stages of parturition are there?

A

3

96
Q

What occurs during the first stage of parturition?

A

myometrial contractions and cervical dilation

97
Q

How long does stage 1 of parturition usually take?

A

2-6 hours

98
Q

What are the typical signs of stage 1 of parturition?

A

separating from the herd, mild contractions and moving around, pelvic ligaments relax

99
Q

What occurs during the second stage of parturition?

A

fetal expulsion: straining and strong contractions, breaking of the allantoic sac, breaking of the amnion sac

100
Q

How long does fetal expulsion usually take?

A

30-60 minutes in cows and 2 hours in heifers

101
Q

What does straining and strong contraction allow for?

A

stimulation of oxytocin release for dilation of the cervix

102
Q

What occurs in stage three of parturition?

A

fetal membrane expulsion

103
Q

How long does fetal membrane expulsion usually take?

A

6-12 hours

104
Q

When does a cow considered to have a retained fetal membrane?

A

when it hasn’t been expelled 12 hours after fetal expulsion

105
Q

How is the fetal membrane expelled?

A

chorionic villi must dislodge from crypts and endometrium (caruncles)

106
Q

On average, when do goats and sheep hit puberty?

A

6 months

107
Q

What is the average length of the goat estrous cycle?

A

21

108
Q

What is the average length of the sheep estrous cycle?

A

17

109
Q

After estrus, when does the goat usually ovulate?

A

12-36 hours

110
Q

After estrus, when does the sheep usually ovulate?

A

24-30 hours

111
Q

What is the main difference between the estrous cycle in small ruminants and the bovine?

A

they are short day seasonal breeders

112
Q

How long is gestation in goats?

A

147-155 days

113
Q

How long is gestation in sheep?

A

145-150 days

114
Q

Typically how many follicular waves do small ruminants have?

A

three to four

115
Q

What is the dominant follicular size in the small ruminant?

A

5 mm

116
Q

What do long light days do in the small ruminant?

A

inhibit the pineal gland from releasing melatonin

117
Q

What is seasonal breeding regulated by?

A

RF amide-relatedd peptide neurons that are present in the mediobasal hypothalamus

118
Q

What are RFRP neurons regulated by?

A

melatonin

Histology Pt. 2 (52 decks)

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