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Physiology III > Lecture 7: pregnancy and Parturition > Flashcards

Lecture 7: pregnancy and Parturition Flashcards

1
Q

When do primary oocysts arrest during embryonic development

A

Prophase I of meiosis

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2
Q

What stage of oogenesis is gonadotropin independent

A

Mitosis and 1st meiosis division

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3
Q

What stage of oogenesis is gonadotropin dependent

A

After puberty when meiosis resumes to generate secondary oocyte—> mature ovum

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4
Q

Meiosis 2 occurs at ___

A

Fertilization

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5
Q

LH surge allows the ___ in the dominant follicle to be lifted

A

Meiotic arrest

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6
Q

When does fertilization occur

A

Time of second meiotic division

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7
Q

Describe the steps from LH surge to fertilization

A
  1. LH surge to lift meiotic arrest and generate secondary oocyte
  2. Ovulation occurs to generate optid
  3. Fertilization occurs and generates zygote that will briefly have male and female pro nucleus
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8
Q

What inhibits meiosis prior to ovulation

A

Oocyte inhibiting factor and luteinizing inhibiting factor

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9
Q

How does oocyte inhibiting factor inhibit meiosis prior to ovulation

A

Keeps oocyte in prophase 1

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10
Q

How does luteinizing inhibiting factor prevent meiosis prior to ovulation.

A

Prevents granulosa cells from becoming luteal tissue

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11
Q

Pre-ovulatory LH surge will breakdown what to release inhibition of meiosis

A

Breakdown of gap junctions between granulosal cells and oocyte

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12
Q

What happens after the breakdown of granulosal cells and oocyte

A
  1. Remove meiotic inhibition
  2. First polar body
  3. Haploid oocyte
  4. Fertilization
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13
Q

Where do dogs, cats, cow, sheep and primates ejaculate into

A

Cranial vagina

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14
Q

Where do pigs and camelids ejaculate into

A

Cervix

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15
Q

Where do horses ejaculate into

A

Uterus

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16
Q

What is fractionation of sperm

A

Methods that minimize sperm loss

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17
Q

Rodents fractionation of ejaculate

A

Produce cervical plug

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18
Q

Horse fractionation of ejaculate

A

Initial ejaculate is sperm-rich and subsequent ejaculate is viscous

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19
Q

Dog fractionation ejaculate

A

Have 3, final is thought to force sperm into uterus

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20
Q

Describe the sequence of events following deposition of spermatozoa into female tract

A
  1. Immediate transport into cervix/uterus
  2. Cervix- “priveleged path” removal of non-motile sperm, removal of some abnormalities
  3. Uterus- capacitation initiated
  4. Oviduct- docking to oviductal cells, capacitation completed, hyperactive motility
  5. Fertilization- acrosome reaction, spermatozoon penetrate oocyte, male and female pronuclei form
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21
Q

What part of female reproductive tract is the “privileged path” removals non-motile sperm and abnormalities

A

Cervix

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22
Q

Where is capacitation initiated

A

Uterus

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23
Q

Where is capacitation completed

A

Oviduct

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24
Q

What increases sperm motility

A

Ca2+ influx

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25
Q

Sperm motility in cervical canal requires what pH

A

Alkaline

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26
Q

Alkaline secretions in the semen from the male’s ___ elevate pH

A

Prostate

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27
Q

What is the role of estrogen in sperm motility

A

Makes cervix mucous watery, facilitating sperm motility

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28
Q

What is responsible for sperm transport in uterine cavity

A

Myometrial contractions

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29
Q

Natural conception lubrication causes what to happen to the sperm

A

Cholesterol withdrawal to expose acrosome cap, redistribute surface proteins, Ca2+ influx to increase motility

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30
Q

What is present in ejaculate that signals to the uterus to activate myometrial contractions

A

Prostaglandins

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31
Q

The myometrium is ___ primed tissue that helps provide sperm motility

A

Estrogen

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32
Q

Upon reaching the ovum what barriers must the sperm break through

A

Corona radiata and zona pellucida via acrosome cap

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33
Q

Oocytes are in meiotic arrest before ____

A

Ovulation

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34
Q

What are ZP molecules

A

Glycoproteins that occur on the zona pellucida

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35
Q

Where are ZP receptors located

A

On sperm

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36
Q

ZP specificity is one factor that limits ___

A

Fertilization to within species

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37
Q

What intimates the acrosomal reaction

A

ZP3 binding to ZP3 receptors

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38
Q

What is the function of ZP2

A

Hold the sperm in place

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39
Q

What happens once sperm penetrates the zona pellucida

A

Fertilin on sperm can bind fertilin receptors on the egg to influx Ca2+ into ovum this is called the zona reaction

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40
Q

What does the zona reaction result in

A

Spread of depolarization over the surface of the egg and immediate release of cortical granules which hardens the zona pellucida to block further ZP1-4 signaling from other sperm, preventing polyspermy

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41
Q

What is the 4-8 cell, non-differentiated pre hatching cells known as

A

Morula

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42
Q

What is a blastocyst

A

Result of fluid accumulation, pre-hatching

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43
Q

What two cell types occur prior to hatching

A

Trophoblasts and inner cell mass

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44
Q

What are trophoblasts responsible for

A

Establish communication between mother and fetus, regulate pregnancy

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45
Q

What do inner cell mass cells become

A

Somatic and germ tissue

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46
Q

How does hatching occur

A

Proteolytic enzymes weaken the zona pellucida and pressure increases within the blastocele

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47
Q

When does hatching occur in cows

A

9-11 days

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48
Q

When does hatching occur in sheep

A

7-8 days

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49
Q

When does hatching occur in swine

A

6 days

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50
Q

When does hatching occur in the bitch

A

13-15 days

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51
Q

When does hatching occur in the queen

A

10-12 days

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52
Q

Where does fertilization occur in female reproductive tract

A

Oviduct

53
Q

Two oviducts/fallopian tubes attach to

A

Uterus

54
Q

During artificial insemination where should sperm be placed in order to minimize retrograde sperm loss

A

Uterus

55
Q

How long does migration of developing zygote and blastocyst take

A

Several days to weeks

56
Q

Maternal recognition requires the distribution of ___ across a wide area of endometrium

A

Pregnancy factors

57
Q

Pregnancy factors are required to rescue the ___ to maintain pregnancy

A

Corpus luteum

58
Q

PGF2alpha induces what

A

Luteolysis

59
Q

What do cows and ewe release from trophoblasts to block oxytocin receptors in uterus, thus inhibiting PGF2alpha

A

Interferon-tau

60
Q

Interferon-tau allows ___to be recognized

A

Pregnancy

61
Q

What is a reliable marker for conception in cows at days 17–20 post ovulation

A

Interferon-tau

62
Q

What secretes interferon-tau

A

Trophoblasts

63
Q

In sows ___ is released from trophoblast to recognize pregnancy

A

Estrogen

64
Q

Describe the mechanism in how estrogen allows the sows to recognize pregnancy

A

Estrogen reroutes PGF2alpha back to uterus so it doesn’t act on CL and cause regression

65
Q

Luteal oxytocin stimulates endometrium to secrete ___in non-pregnant females

A

Prostaglandins

66
Q

___secretion is suppressed if there is an embryo present

A

Prostaglandin

67
Q

what hormone remains high during pregnancy

A

Progesterone

68
Q

is this graph indicative or not indicative of conceptus present

A

Conceptus is present, progesterone levels are high and PGF2alpha levels are low

69
Q

Is this graph indicative or not indicative or conceptus present

A

no conceptus present, progesterone drops and PGF2alpha rises

70
Q

What hormone is released by endometrial cups (horses) of placenta at day 40-70 days or pregnancy

A

Equine chorionic gonadotropin (eCG)

71
Q

Soon after ovulation and early days of gestation what happens to progesterone levels

A

Drops

72
Q

What reactivates progesterone levels in horses

A

Equine chorionic gonadotropin

73
Q

What is the stimulus of release for eCG

A

Spontaneous release

74
Q

What is the target of eCG

A

CL/ovary

75
Q

What is the effect of eCG

A

LH-like characteristics in mares, enhances progesterone production by primary CL and triggers ovulation of additional follicles to create secondary CL

76
Q

Which species lack luteotrophic mechanisms

A

Dogs and cats

77
Q

How long does CL survive independent of pregnancy in dogs

A

60-70 days

78
Q

In dogs, luteal function begins ___ and is supported by ___, followed later by ___

A

Autonomously, LH and prolactin

79
Q

Relaxin ___luteal activity

A

Enhances

80
Q

Relaxin enhances ___

A

Progesterone

81
Q

T or F: a signal from the embryo in dogs and cats is not necessary because the CL are not lysed before normal pregnancy is established

A

True! CL survives 60-70 days

**unlike cows which require IFN-tau

82
Q

How long does CL last in cats independent of pregnancy

A

35-40 days

83
Q

Relaxin is a ___hormone

A

Placental

84
Q

What hormones maintain CL in cats

A

Progesterone and relaxin

85
Q

When does implantation adhesion occur

A

Blastocyst implantation begins when cell adhesion molecules adhere to the endometrium and trophoblasts enzymes erode the uterine wall

86
Q

When does implantation invasion occur

A

Trophoblasts cells invade and blastocyst is embedded within the endometrium

87
Q

___cells completely cover the developing embryo

A

Endometrial

88
Q

When does implantation and invasion of endometrium occur

A

When endometrium is at its peak thickness and secretion

89
Q

The placenta performs the functions of the ___system, the ___system, and ____ for the fetus

A

Digestive, respiratory and kidney

90
Q

What structure prevents immunological rejection of fetus

A

Placenta

91
Q

What essential pregnancy hormones does the placenta secrete

A
  1. Estrogen
  2. Progesterone
  3. Equine chorionic gonadotropin
92
Q

In horses, what hormone maintains CL until placenta takes over function in last 2 trimesters

A

Equine chorionic gonadotropin

93
Q

How is gestation maintained in all species

A

Progesterone

94
Q

What structure takes over the corpus luteum later in gestation

A

Placenta

95
Q

Progesterone inhibits ___contractions and maintains pregnancy

A

Myometrial contractions

96
Q

___ blocks the formation of gap junctions during pregnancy

A

Progesterone

97
Q

What prevents contractility of uterus during pregnancy

A

Progesterone

98
Q

What promotes endometrial gland growth during pregnancy

A

Progesterone

99
Q

What stimulates secretory activity of oviduct and endometrial glands to provide nutrients during pregnancy

A

Progesterone

100
Q

What hormone has a thermogenesic effect during pregnancy

A

Progesterone

101
Q

When does placenta take over control of CL in cows

A

6-8 months

102
Q

When does placenta take over control of CL in ewe

A

50 days

103
Q

When does placenta take over control of CL in mare

A

70 days

104
Q

Where does progesterone synthesis start: mother, placenta or fetus?

A

Mother

105
Q

Where is cholesterol converted to pregnenolone and then progesterone in pregnancy

A

Occurs in placenta

106
Q

What is estriol

A

Estrogen that is derived from the placental-fetal unit

107
Q

What is estriol useful to determine

A

Placental competency

108
Q

Describe the steps and locations of estriol synthesis

A
  1. Starts in mother with cholesterol
  2. Cholesterol enters placenta and is converted to pregnenolone
  3. Pregnenolone travels from placenta to fetus
  4. Fetus converts pregnenolone to DHEA sulfate and then 16-OH DHEA-sulfate
  5. 16-OH DHEA sulfate returns to placenta and converted to estriol
  6. Estriol returns to mother
109
Q

When during pregnancy does estrogen dramatically increase

A

End

110
Q

What does peak estrogen at end of pregnancy do to prepare for baby

A
  1. Increased growth of myometrium- muscles for labor
  2. Development of ductile system of mammaries
  3. Relax and soften pelvic ligaments
  4. Stimulates prolactin release
111
Q

What does estrogen inhibit at end of pregnancy

A

Lactation

112
Q

How does estrogen inhibit lactation at end of pregnancy

A
  1. Antagonizes prolactin effect on mammary glands, suppressing milk synthesis
  2. Inhibits lactalbumin- required for lactose synthesis
113
Q

What initiates stage 1 of parturition

A

Fetal adrenal corticoids

114
Q

During stage 1 of parturition what is progesterone converted into

A

Estradiol

115
Q

What happens to corpus luteum during stage 1 parturition

A

Luteolysis

116
Q

What does PGF2alpha do during stage I parturition

A

Contributes to myometrial contractions

117
Q

What stage does the preparation of Birth canal via lubrication and relaxation of pelvic ligaments occur

A

Stage 1

118
Q

What happens during stage 2 parturition

A

Delivery, fetus passes through pelvic canal

119
Q

What happens during stage III parturition

A

Fetal membranes are delivered

120
Q

During stage III myometrial contractions and PGF2alpha surges occur to…

A

Reduce uterus size and release of membranes

121
Q

What axis is activated towards end of pregnancy, stage I parturition

A

Fetal hypothalamus-pituitary adrenal axis

122
Q

Fetal cortisol activates what enzyme to shunt synthesis from progesterone to estrogen

A

17-alpha hydroxylase

123
Q

During conversion of progesterone to estrogen in stage I of parturition the myometrium becomes more active by

A

Increasing secretory activity of reproductive tract and opens the cervix

124
Q

Fetal cortisol causes the placenta to produce ___

A

PGF2alpha

125
Q

Fetal cortisol stimulates placenta to produce PGF2alpha which will stimulate release of ___loosening ligaments and softening birth canal

A

Relaxin

126
Q

What two hormones contribute most to uterine contractions

A

Oxytocin and prostaglandins

127
Q

Delivery of fetus through cervical canal is mediated by ___

A

Oxytocin

128
Q

Labor is initiated when

A

Oxytocin receptor concentration reaches critical threshold

Physiology III (34 decks)

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