Lecture 7: pregnancy and Parturition Flashcards
1
Q
When do primary oocysts arrest during embryonic development
A
Prophase I of meiosis
2
Q
What stage of oogenesis is gonadotropin independent
A
Mitosis and 1st meiosis division
3
Q
What stage of oogenesis is gonadotropin dependent
A
After puberty when meiosis resumes to generate secondary oocyte—> mature ovum
4
Q
Meiosis 2 occurs at ___
A
Fertilization
5
Q
LH surge allows the ___ in the dominant follicle to be lifted
A
Meiotic arrest
6
Q
When does fertilization occur
A
Time of second meiotic division
7
Q
Describe the steps from LH surge to fertilization
A
- LH surge to lift meiotic arrest and generate secondary oocyte
- Ovulation occurs to generate optid
- Fertilization occurs and generates zygote that will briefly have male and female pro nucleus
8
Q
What inhibits meiosis prior to ovulation
A
Oocyte inhibiting factor and luteinizing inhibiting factor
9
Q
How does oocyte inhibiting factor inhibit meiosis prior to ovulation
A
Keeps oocyte in prophase 1
10
Q
How does luteinizing inhibiting factor prevent meiosis prior to ovulation.
A
Prevents granulosa cells from becoming luteal tissue
11
Q
Pre-ovulatory LH surge will breakdown what to release inhibition of meiosis
A
Breakdown of gap junctions between granulosal cells and oocyte
12
Q
What happens after the breakdown of granulosal cells and oocyte
A
- Remove meiotic inhibition
- First polar body
- Haploid oocyte
- Fertilization
13
Q
Where do dogs, cats, cow, sheep and primates ejaculate into
A
Cranial vagina
14
Q
Where do pigs and camelids ejaculate into
A
Cervix
15
Q
Where do horses ejaculate into
A
Uterus
16
Q
What is fractionation of sperm
A
Methods that minimize sperm loss
17
Q
Rodents fractionation of ejaculate
A
Produce cervical plug
18
Q
Horse fractionation of ejaculate
A
Initial ejaculate is sperm-rich and subsequent ejaculate is viscous
19
Q
Dog fractionation ejaculate
A
Have 3, final is thought to force sperm into uterus
20
Q
Describe the sequence of events following deposition of spermatozoa into female tract
A
- Immediate transport into cervix/uterus
- Cervix- “priveleged path” removal of non-motile sperm, removal of some abnormalities
- Uterus- capacitation initiated
- Oviduct- docking to oviductal cells, capacitation completed, hyperactive motility
- Fertilization- acrosome reaction, spermatozoon penetrate oocyte, male and female pronuclei form
21
Q
What part of female reproductive tract is the “privileged path” removals non-motile sperm and abnormalities
A
Cervix
22
Q
Where is capacitation initiated
A
Uterus
23
Q
Where is capacitation completed
A
Oviduct
24
Q
What increases sperm motility
A
Ca2+ influx
25
Sperm motility in cervical canal requires what pH
Alkaline
26
Alkaline secretions in the semen from the male’s ___ elevate pH
Prostate
27
What is the role of estrogen in sperm motility
Makes cervix mucous watery, facilitating sperm motility
28
What is responsible for sperm transport in uterine cavity
Myometrial contractions
29
Natural conception lubrication causes what to happen to the sperm
Cholesterol withdrawal to expose acrosome cap, redistribute surface proteins, Ca2+ influx to increase motility
30
What is present in ejaculate that signals to the uterus to activate myometrial contractions
Prostaglandins
31
The myometrium is ___ primed tissue that helps provide sperm motility
Estrogen
32
Upon reaching the ovum what barriers must the sperm break through
Corona radiata and zona pellucida via acrosome cap
33
Oocytes are in meiotic arrest before ____
Ovulation
34
What are ZP molecules
Glycoproteins that occur on the zona pellucida
35
Where are ZP receptors located
On sperm
36
ZP specificity is one factor that limits ___
Fertilization to within species
37
What intimates the acrosomal reaction
ZP3 binding to ZP3 receptors
38
What is the function of ZP2
Hold the sperm in place
39
What happens once sperm penetrates the zona pellucida
Fertilin on sperm can bind fertilin receptors on the egg to influx Ca2+ into ovum this is called the zona reaction
40
What does the zona reaction result in
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
41
What is the 4-8 cell, non-differentiated pre hatching cells known as
Morula
42
What is a blastocyst
Result of fluid accumulation, pre-hatching
43
What two cell types occur prior to hatching
Trophoblasts and inner cell mass
44
What are trophoblasts responsible for
Establish communication between mother and fetus, regulate pregnancy
45
What do inner cell mass cells become
Somatic and germ tissue
46
How does hatching occur
Proteolytic enzymes weaken the zona pellucida and pressure increases within the blastocele
47
When does hatching occur in cows
9-11 days
48
When does hatching occur in sheep
7-8 days
49
When does hatching occur in swine
6 days
50
When does hatching occur in the bitch
13-15 days
51
When does hatching occur in the queen
10-12 days
52
Where does fertilization occur in female reproductive tract
Oviduct
53
Two oviducts/fallopian tubes attach to
Uterus
54
During artificial insemination where should sperm be placed in order to minimize retrograde sperm loss
Uterus
55
How long does migration of developing zygote and blastocyst take
Several days to weeks
56
Maternal recognition requires the distribution of ___ across a wide area of endometrium
Pregnancy factors
57
Pregnancy factors are required to rescue the ___ to maintain pregnancy
Corpus luteum
58
PGF2alpha induces what
Luteolysis
59
What do cows and ewe release from trophoblasts to block oxytocin receptors in uterus, thus inhibiting PGF2alpha
Interferon-tau
60
Interferon-tau allows ___to be recognized
Pregnancy
61
What is a reliable marker for conception in cows at days 17–20 post ovulation
Interferon-tau
62
What secretes interferon-tau
Trophoblasts
63
In sows ___ is released from trophoblast to recognize pregnancy
Estrogen
64
Describe the mechanism in how estrogen allows the sows to recognize pregnancy
Estrogen reroutes PGF2alpha back to uterus so it doesn’t act on CL and cause regression
65
Luteal oxytocin stimulates endometrium to secrete ___in non-pregnant females
Prostaglandins
66
___secretion is suppressed if there is an embryo present
Prostaglandin
67
what hormone remains high during pregnancy
Progesterone
68
is this graph indicative or not indicative of conceptus present
Conceptus is present, progesterone levels are high and PGF2alpha levels are low
69
Is this graph indicative or not indicative or conceptus present
no conceptus present, progesterone drops and PGF2alpha rises
70
What hormone is released by endometrial cups (horses) of placenta at day 40-70 days or pregnancy
Equine chorionic gonadotropin (eCG)
71
Soon after ovulation and early days of gestation what happens to progesterone levels
Drops
72
What reactivates progesterone levels in horses
Equine chorionic gonadotropin
73
What is the stimulus of release for eCG
Spontaneous release
74
What is the target of eCG
CL/ovary
75
What is the effect of eCG
LH-like characteristics in mares, enhances progesterone production by primary CL and triggers ovulation of additional follicles to create secondary CL
76
Which species lack luteotrophic mechanisms
Dogs and cats
77
How long does CL survive independent of pregnancy in dogs
60-70 days
78
In dogs, luteal function begins ___ and is supported by ___, followed later by ___
Autonomously, LH and prolactin
79
Relaxin ___luteal activity
Enhances
80
Relaxin enhances ___
Progesterone
81
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
True! CL survives 60-70 days
**unlike cows which require IFN-tau
82
How long does CL last in cats independent of pregnancy
35-40 days
83
Relaxin is a ___hormone
Placental
84
What hormones maintain CL in cats
Progesterone and relaxin
85
When does implantation adhesion occur
Blastocyst implantation begins when cell adhesion molecules adhere to the endometrium and trophoblasts enzymes erode the uterine wall
86
When does implantation invasion occur
Trophoblasts cells invade and blastocyst is embedded within the endometrium
87
___cells completely cover the developing embryo
Endometrial
88
When does implantation and invasion of endometrium occur
When endometrium is at its peak thickness and secretion
89
The placenta performs the functions of the ___system, the ___system, and ____ for the fetus
Digestive, respiratory and kidney
90
What structure prevents immunological rejection of fetus
Placenta
91
What essential pregnancy hormones does the placenta secrete
1. Estrogen
2. Progesterone
3. Equine chorionic gonadotropin
92
In horses, what hormone maintains CL until placenta takes over function in last 2 trimesters
Equine chorionic gonadotropin
93
How is gestation maintained in all species
Progesterone
94
What structure takes over the corpus luteum later in gestation
Placenta
95
Progesterone inhibits ___contractions and maintains pregnancy
Myometrial contractions
96
___ blocks the formation of gap junctions during pregnancy
Progesterone
97
What prevents contractility of uterus during pregnancy
Progesterone
98
What promotes endometrial gland growth during pregnancy
Progesterone
99
What stimulates secretory activity of oviduct and endometrial glands to provide nutrients during pregnancy
Progesterone
100
What hormone has a thermogenesic effect during pregnancy
Progesterone
101
When does placenta take over control of CL in cows
6-8 months
102
When does placenta take over control of CL in ewe
50 days
103
When does placenta take over control of CL in mare
70 days
104
Where does progesterone synthesis start: mother, placenta or fetus?
Mother
105
Where is cholesterol converted to pregnenolone and then progesterone in pregnancy
Occurs in placenta
106
What is estriol
Estrogen that is derived from the placental-fetal unit
107
What is estriol useful to determine
Placental competency
108
Describe the steps and locations of estriol synthesis
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
When during pregnancy does estrogen dramatically increase
End
110
What does peak estrogen at end of pregnancy do to prepare for baby
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
What does estrogen inhibit at end of pregnancy
Lactation
112
How does estrogen inhibit lactation at end of pregnancy
1. Antagonizes prolactin effect on mammary glands, suppressing milk synthesis
2. Inhibits lactalbumin- required for lactose synthesis
113
What initiates stage 1 of parturition
Fetal adrenal corticoids
114
During stage 1 of parturition what is progesterone converted into
Estradiol
115
What happens to corpus luteum during stage 1 parturition
Luteolysis
116
What does PGF2alpha do during stage I parturition
Contributes to myometrial contractions
117
What stage does the preparation of Birth canal via lubrication and relaxation of pelvic ligaments occur
Stage 1
118
What happens during stage 2 parturition
Delivery, fetus passes through pelvic canal
119
What happens during stage III parturition
Fetal membranes are delivered
120
During stage III myometrial contractions and PGF2alpha surges occur to…
Reduce uterus size and release of membranes
121
What axis is activated towards end of pregnancy, stage I parturition
Fetal hypothalamus-pituitary adrenal axis
122
Fetal cortisol activates what enzyme to shunt synthesis from progesterone to estrogen
17-alpha hydroxylase
123
During conversion of progesterone to estrogen in stage I of parturition the myometrium becomes more active by
Increasing secretory activity of reproductive tract and opens the cervix
124
Fetal cortisol causes the placenta to produce ___
PGF2alpha
125
Fetal cortisol stimulates placenta to produce PGF2alpha which will stimulate release of ___loosening ligaments and softening birth canal
Relaxin
126
What two hormones contribute most to uterine contractions
Oxytocin and prostaglandins
127
Delivery of fetus through cervical canal is mediated by ___
Oxytocin
128
Labor is initiated when
Oxytocin receptor concentration reaches critical threshold
