Exam 2 Flashcards
(143 cards)
1
Q
What are three definitions of puberty?
A
- The desire and ability to mate
- The process of acquiring reproductive competence
- Stage of development characterized by the onset of production and/or release of functional gametes
2
Q
Differences in the hypothalamus of the male and female are established in _____ development.
A
Prenatal
3
Q
What happens to the hypothalamus in the presence and absence of testosterone in development?
A
- Absence: Hypothalamus develops in a feminine way with a surge center and tonic center
- Presence: Hypothalamus is defeminized
4
Q
How is he hypothalamus defeminized in the male?
A
Testosterone enters the brain and is converted to estrogen by aromatase
5
Q
Why does the female hypothalamus not defeminize due to ovarian estrogen?
A
Alpha-fetoprotein binds specifically to circulating estrogen, making it too big to penetrate the blood-brain barrier. Testosterone is small and lipid-soluble, so it can penetrate the barrier.
6
Q
What are the patterns of GnRH and LH secretion like in the postpubertal male?
A
Regular pulses of GnRH and LH every 2-6 hours in the male
7
Q
What are patterns of GnRH and LH secretion like in the postpubertal female?
A
- Tonic center GnRH and LH released similar to the male, every 2-6 hours
- Big surge of GnRH and LH from the surge center once per cycle, every 28 days
8
Q
What are the fundamental requirements for onset of puberty in males and females?
A
- As puberty approaches, GnRH pulses from the tonic center will increase, increasing the release of gonadotropins. Gonadotropins will stimulate the gonads to generate gametes and hormones such as estrogen and testosterone that will stimulate reproductive tissues and secondary sex characteristics.
9
Q
What is limiting during the prepubertal period?
A
Before the onset of puberty, GnRH release from the tonic center occurs every few days. After puberty, it occurs every 2-6 hours. The major limiting factor i sthe failure of the tonic center of the hypothalamus to produce enough GnRH to stimulate elevated gonadotropin secretion.
10
Q
Describe the gonadostat hypothesis. How does it affect the male and female?
A
Before puberty, low steroid levels have high negative feedback on the tonic center. As puberty approaches, the sensitivity to negative feedback decreases, so the pulses of GnRH increase, and LH and FSH increase.
- Female: Increased follicular development, leading to increased serum estrogen, leading to positive feedback at the surge center
- Male: Increased serum testosterone, increased sperm production
11
Q
What are other factors that play a role in the onset of puberty?
A
- Stress
- Body Weight
- Genetics
- Social cues
- Pheromones
- Photoperiod in seasonal breeders
12
Q
What do reproductive cycles, such as estrous or menstrual cycles, provide the female?
A
Multiple opportunities for pregnancy
13
Q
What is anestrus? What times does this occur?
A
- Times when reproductive cycles cease
- Pregnancy
- Prior to puberty
- Menopause
- Stress
- Post-Partum
- Non-breeding season for seasonal breeders
- During lactation
14
Q
Estrous is an _____, Estrus is a _____.
A
- Adjective
- Noun
15
Q
The ____ ____ is the period between consecutive displays of estrus.
A
Estrous cycle
16
Q
_____ is the display of sexual receptivity.
A
Estrus
17
Q
What does it mean for a species to be polyestrus? What are some examples?
A
- Species that are capable of having estrous cycles throughout the year
- Cow, queen, pig, rodents
18
Q
What does it mean for a species to be seasonally polyestrus?
A
-Species whose estrous cycles are limited to a certain season of the year
19
Q
Long day breeders are ____ _____ species. Describe their cycles. Give some species examples.
A
- Seasonally polyestrus
- Begin to cycle in the spring, as the length of day increases
- Mare, hamster
20
Q
Short-day breeders are ______ _____ species. Describe their cycles. Give some species examples.
A
- Seasonally polyestrus
- Begin to cycle in the fall as the day length decreases
- Ewe, doe, elk, nanny
21
Q
What does it mean for a species to be monoestrus? What are some species examples?
A
- Species that have only one estrus per year
- Wolf, fox bear
- The domestic dog is also in this category, but could have 2-4 displays of estrus per year
22
Q
What are the phases of the estrous cycle in farm species?
A
- Follicular Phase
- Luteal Phase
23
Q
The follicular phase is the period from _____ ___ to ______. During the follicular phase, the dominant ovarian structures are the _____, the dominant ovarian hormone is _____, and the corpus luteum is ____ or _____.
A
- Luteal Regression
- Ovulation
- Follicles
- Estrogen
- Regressing
- Regressed
24
Q
The luteal phase is the period from _____ to _____ ______. It is about ____% of the estrous cycle length in many species. During the luteal phase, the dominant ovarian strucutre is the ____ ____, and the primary ovarian hormone is _______.
A
- Ovulation
- Luteal Regression
- 80
- Corpus Luteum
- Progesterone
25
True or False: Antral follicular development occurs during the luteal phase and follicular phase in species with estrous cycles.
True
26
What are the stages of the estrous cycle in farm species?
1. Proestrus
2. Estrus
3. Metestrus
4. Diestrus
27
During _____, the corpus luteum is regressing. This causes a decline in ____ and increase in ____, supported by ____ and _____.
- Proestrus
- Progesterone
- Estrogen
- LH
- FSH
28
_____ is the most recognizable stage of the estrous cycle due to behavioral changes. ____ and _____ ___ are high, and the female permits ____.
- Estrus
- Estrogen
- Sexual Receptivity
- Copulation
29
Describe Metestrus. Circulating estrogen is _____ precipitously, circulating progesterone is _____ gradually, and ____ is occuring in the early part.
- The period between ovulation and the formation of a functioning corpus luteum
- Declining
- Increasing
- Luterinization
30
_____ is the longest stage of the estrous cycle. The ____ ____ is fully functional, and ____ production is high. What defines this period?
- Diestrus
- Corpus Luteum
- Progesterone
- The period from the onset of maximal serum progesterone to early luteolysis
31
What stages of the estrous cycle make up the follicular phase? The luteal phase?
- Follicular: Proestrus and estrus
| - Luteal: Metestrus and diestrus
32
How many estrous cycles per year do wild canids display? Domestic bitches?
- one cycle per year
| - around two
33
When does the estrous cycle occur in dogs?
February through May
34
What are the stages of the estrous cycle in the dog?
Anestrus, proestrus, estrus, diestrus
35
Describe anestrus in the dog.
Limited follicular development, will not achieve maximum estrogen, no estrous behavior or ovulation, low progesterone
36
During proestrus in the dog, ____ development progesses, and serum ____ gradually increases. What is unique to the dog in this stage?
- follicular
- estrogen
- Vaginal swelling and bloody vaginal discharge
37
In the dog, _____ begins shortly after the estrogen peak. Ovulation occurs ____ - ____ days after the LH surge, and fertilization will occur ____ - ____ hours after that.
- Estrus
- 2 to 3
- 48-72
38
True or False: Metestrus in the dog is characterized by declining estrogen and rising progesterone.
False, no designated metestrus in the dog because they are still showing estrous behavior during decreasing estrogen and rising progesterione
39
Describe diestrus in the dog.
It is the period of luteal function lasting 60 days. The length is the same whether the dog is pregnant or open.
40
What does it mean for the cat to be an induced/reflex ovulator?
Mating is required for a neural trigger to induce ovulation
41
What is the breeding season for cats?
For outdoor cats, it is January through September. It is longer for indoor cats due to increased light exposure.
42
In the absence of mating, the queen enters estrus every ___ days. Estrus lasts ____ days.
- 17
| - 9
43
What two things occur during estrus of the cat?
1. Sexual receptivity
| 2. Follicles capable of ovulating are present
44
What does stimulating of the vagina and cervix during mating lead to in the cat?
Reflex release of GnRH, LH surge, ovulation, and CL formation
45
What does the non-fertile mating of a reflex ovulator lead to?
Pseudopregnancy
46
_____ is a period of luteal function that is about half the length of a normal pregnancy. What is the evolutionary advantage to this system?
- Pseuopregnancy
| - The induced ovulator comes back into heat sooner than CL function for the entire length of a normal pregnancy
47
What is gestational anestrus?
No signs of estrus or reproductive cycles during pregnancy
48
During gestational anestrus, what does progesterone do?
Progesterone has negative feedback on GnRH, decreasing LH and FSH, and decreasing follicular development and the absence of ovulation
49
True or False: A small percentage of cows and ewes will show estrus during pregnancy
True
50
What is the cause and evolutionary advantage of seasonal anestrus?
- Cause: Reduction in the frequency of GnRH pulses from the tonic center
- Advantage: Young are born when the weather is nicer
51
What occurs in the onset of seasonal cyclicity?
Frequency of GnRH pulses from the tonic center increase, LH and FSH increase, follicular development and ovulation
52
Why is the first ovulation after anestrus called a "silent ovulation"?
It is not accompanied by estrus behavior
53
What effect does photoperiod have on cyclicity?
As day length increases, excitation of retinal neurons increases leading to activation of inhibitory neurons, melatonin from the pineal gland decreases
54
Melatonin is secreted at ____.
Night
55
What happens to short day breeders during long days?
During long days, nights are short with low melatonin secretion. Low melatonin results in decreased frequency of GnRH pulses from the tonic center in short-day breeders.
56
What happens to long day breeders during long days?
During long days, nights are short with low melatonin secretion. Low melatonin results in increased frequency of GnRH pulses from the tonic center in long-day breeders.
57
Low melatonin causes ____ GnRH pulses in long-day breeders and ____ GnRH pulses in short day breeders.
- Increased
| - Decreased
58
Define the menstrual cycle.
The interval between consecutive displays of menstruation
59
_____ is the cyclic uterine bleeding and sloughing of the endometrium
Menstruation
60
True or False: There is no estrus in species that menstruate, so there is no discrete period of sexual receptivity.
True
61
What is unique to the menstrual cycle?
Distinct follicular and luteal phases. Each is equal halves of the cycle.
62
Increased estrogen causes what for the endometrium and smooth muscle?
Proliferation
63
Following ovulation, the _____ ____ forms and produces ____, _____ , and ____.
- Corpus Luteum
| - Estrogen, inhibin, progesterone
64
What occurs during menstruation?
- Decreased progesterone and estrogen
- Loss of hormonal support of the uterine lining
- Sloughing of uterine lining
65
Describe the vaginal discharge that occurs in the dog.
- Occurs during proestrus
- Bleeding is due to diapedesis
- Bleeding is related to rising estrogen
66
Describe the vaginal discharge that occurs in the cow.
- Metestrous bleeding sometimes occurs
- Related to declining estrogen
- If metestrous bleeding occurs, the animal was in heat about 48 hours earlier
67
Describe the vaginal discharge that occurs in primates.
- Menstruation
- Declining serum progesterone and estrogen
- Lost of endometrium support
- Tissue loss and blood loss
68
At the start of the follicular phase, ____ from the previous cycle has dropped.
Progesterone
69
When serum inhibin is high enough, it causes a decrease in ______ and acts directly on the _____ _____.
- Inhibin
| - Anterior pituitary
70
Estrogen _____ LH and FSH from the anterior pituitary in normal serum levels.
Inhibits
71
How does estrogen cause positive feedback?
- When it exceeds a threshold in the absence of progesterone, it triggers the GnRH surge center to increase the frequency of GnRH pulses.
- This happens once per cycle
72
The surge center is sensitive to ____ feedback of estrogen and releases ____ amplitude, ____ frequency pulses of GnRH
- Positive
- High
- High
73
What hormonal changes take place during the follicular phase?
As the CL regress, serum progesterone declines, which reduces the negative feedback of progesterone on the hypothalamus and anterior pituitary. LH and FSH begin to rise and stimulate estrogen production. When estrogen exceeds a threshold, positive feedback triggers an LH surge, inducing ovulation and luteinization dominant follicle
74
_____ is the development of follicles.
Folliculogenesis
75
What are the stages of follicular development?
1. Primordial Follicle
2. Primary Follicle
3. Secondary Follicle
4. Tertiary Follicle
5. Mature Follicle
76
What are two characteristics of the primordial follicle?
1. Single layer of squamous granulosal cells
| 2. Resting state
77
What is one characteristic of the primary follicle?
1. Single layer of cuboidal granulosa cells
78
What are two characteristics of the secondary follicle?
1. Proliferation of granulosa cells to have two or more layers
2. Zona pellucida forms
79
The ____ _____ is a tough outer covering composed of mucopolysaccharides that form a thick translucent layer surrounding the vitelline membrane.
Zona Pellucida
80
The oocyte cell membrane is commonly called the ____ _____.
Vitelline Membrane
81
_____ _____ are at the end of granulosal cell processes and extend into the zona pellucida to the oocyte to support it.
Gap Junctions
82
Describe a characteristic of the tertiary follicle.
The antrum forms and is a space where follicular fluid accumulates
83
Describe two characteristics of the mature follicle.
1. Large antrum
| 2. Capable of ovulation
84
The ____ ____ is a mound of granulosa cells surrounding the oocyte. The ___ ___ is the two or three layers closest to the oocyte.
- Cumulus Oorphorus
| - Corona Radiata
85
True or False: Growth to the secondary follicle stage requires LH and FSH.
False, growth to the secondary follicle stage is independent of gonadotropins
86
How does FSH affect follicular growth?
- Stimulates granulosa cell mitosis
- Stimulates follicular fluid secretion
- Stimulates estrogen production
- Stimulates acquisition of LH receptors on granulosa cells
87
What hormones are needed for antrum formation and final growth?
FSH and LH
88
How does LH affect follicular growth?
- Acts on thecal cells to stimulate proliferation
- Stimulates estrogen production
- Acts on granulosa cells of mature follicles
89
When do growth and regression of antral follicles occur in the estrous cycle and and the menstrual cycle?
- Estrous cycle: Occurs throughout the cycle, even in the luteal phase
- Menstrual Cycle: Only occurs in the follicular phase
90
What three steps occur after follicles reach an antral stage of developmnent?
1. Recruitment
2. Selection
3. Dominance
91
Describe the a recruitment of follicles.
- A cohort of small follicles begin to grow and produce estrogen
- The follicle that reaches a certain size first is "selected"
92
Describe the selection of follicles.
- A follicle is selected to become dominant, and any follicle not selected is called subordinant and and undergoes atresia
- Selected follicles produce increasing amounts of estrogen and inhibin and continue to grow
93
Describe the dominant follicle.
- Enhanced blood supply
- Granulosa cells acquire LH receptors
- Products inhibit gonadotropin secretion, and they survive under diminishing serum gonadotropin
94
How are dominant follicles able to survive under diminishing gonadotropin concentrations?
- Better blood supply
| - Granulosal acquire LH receptors so they can now respond to LH and FSH
95
When can atresia of follilces occur?
Any time during follicular delelopment
96
True or False: Preantral follicular growth is much slower than post-antral growth.
True
97
Theca cells lie _____ the basement membrane of the follicle. They produce _______ and have _____ receptors.
- Outside
- Testosterone
- LH
98
Granulosa cells lie _____ the basement membrane of the follicle. They have ____ receptors. They have the enzyme _____ that catalyzes the conversion of testosterone to estrogen.
- Inside
- FSH
- Aromatase
99
Describe the two-cell, two-gonadotropin model of estrogen synthesis.
LH binds to its receptor on thecal cells an stimulates testosterone production. Testosterone diffuses through the basement membrane into granulosa cells. FSH binds to its receptor on granulosa cells and stimulates the aromatase enzyme, which catalyzes the conversion of testosterone to estrogen.
100
When do granulosa cells acquire LH receptors?
Only preovulatory follicles have LH receptors
101
Describe the key events of ovulation.
1. LH surge
2. Increased local prostaglandin (PGE2) and histamine, which increases blood flow and follicular pressure
3. Increased local prostaglandin (PGF2a) causes smooth muscle contractions and increased follicular pressure
4. Increased progesterone increases the activity of collagenase
5. Cell death and collagen breakdown causes cell separation and release of the oocyte from the follicle wall and weakening of the follicle wall
6. Ovulation
102
How do oogonia replicate?
Mitosis
103
Are primary oocytes considered 2n or 1n?
2n
104
All occytes in the follicles of the ovary are ______ oocytes until ovulation occurs.
Primary
105
The ______ ______ triggers the first meiotic division. This occurs near _____. Which oocytes does this happen in?
- LH surge
- Ovulation
- Only those housed in mature (preovulatory) follicles
106
What are the results of the first meiotic division?
A secondary oocyte and a polar body
107
A _____ oocyte is what is ovulated.
Secondary
108
What triggers the second meiotic division?
Fertilization
109
______ is the process of generating germ cells with a haploid number of chromosomes.
Meiosis
110
What is the end result of meiosis?
A primary oocyte becomes a fertilized ovum and two polar bodies
111
Mitosis and Meiosis start with _____ _____.
DNA replication
112
Meiosis one is a ______ division. Why is this?
- Reductional
| - Homologous pairs of chromosomes separate
113
Mitosis and Meiosis two is a ____ division. Why is this?
- Equational
| - Sister chromatids separate, but the number of chromosomes does not change
114
Describe the changes in oocyte numbers throughout the life span of the woman.
There is a prenatal peak, further decline prior to puberty, decline to near zero at menopause
115
The LH surge causes the breakdown of ____ ____ in the follicle.
Gap Junctions
116
Describe the roles of granulosa cells and the LH surge in meiosis.
- Granulosa cells provide a meiotic inhibitor to oocytes via the gap junctions
- The LH surge causes a breakdown of the gap junctions, contributing to resumption of meiosis
117
After ovulation the oocyte is a ____ oocyte. Is it 1N or 2N?
- Secondary
| - 1N
118
How long does the luteal phase last?
From the time of ovulation to the time of luteal regression
119
What stages of the estrous cycle are included in the luteal phase?
-Metestrus and Diestrus
120
What three things does the luteal phase include?
1. Formation of the CL through luteinization
2. Function of the CL
3. Regression of the CL through luteolysis
121
What occurs during luteinization?
- Follicle wall ruptures, developing a corpora hemorrhagica
- Basement membrane begins to degrade and separate granulosa cells and thecal cells
- Walls of the follicle collapse inward and leave an antrum
122
What do granulosa cells give rise to after luteinization? Thecal cells?
- Granulosa Cells: Large Luteal Cells
| - Thecal Cells: Small Luteal Cells
123
How does progesterone affect the hypothalamus?
- Negative feedback on GnRH secretion
- At the surge center, it prevents GnRH surges
- At the tonic center, it reduces GnRH pulse frequency and amplitude
124
How does progesterone affect the anterior pituitary?
-Negative feedback on cells that secrete LH and FSH
125
How does progesterone affect the behavioral centers of the brain?
It blocks estrous behavior
126
How does progesterone affect the endometrium and myometrium of the uterus?
- Endometrium: Progesterone stimulates development of uterine glands and secretion of uterine milk from these glands
- Myometrium: Progesterone inhibits muscular contractions
127
How does progesterone affect the mammary gland?
It promotes alveolar development to prepare the pregnant animal for lactation
128
What supports the CL?
LH is luteotropic, meaning it supports the CL, and stimulates progesterone production. It is necessary for CL maintenance and is regulated through negative feedback of progesterone.
129
Where does the luteolytic signal come from in the mare, cow, sheep, and pig and what cis the signal?
- Uterus
| - Release of prostaglandin (PGF2a) causes CL regression in the absence of pregnancy
130
In higher primates, where does the luteolytic signal come from?
Directly from the CL
131
In the cow, sheep, pig, and mare, if you did a total hysterectomy, what would happen to the CL?
It would be maintained since the luteolytic signal comes from the uterus
132
What would happen to the CL if you did a total hysterectomy in higher primates?
There would be no effect since the CL itself makes the prostaglandin that leads to luteinization
133
Why is the effect of a unilateral hysterectomy in the ewe and cow dependent on whether the horn that remains is adjacent or opposite to the ovary with the CL?
- PGF2a has a local effect
- PGF2a from the uterus reaches the ovary through a local veno-arterial pathway, it is transferred from a uterine vein to an ovarian artery and acts on the CL
134
Describe the local and systemic effect of PGF2a in the sheep and cow, pig, horse, and higher primates.
- Sheep and Cow: Rapidly metabolized (90% with one pass through the lungs) so it must have mostly a local effect because levels cannot be built up systemically
- Pig: Only 18-40% metabolized, so systemic delivery prevails, but still have the veno-arterial pathway
- Horse: Veno-arterial pathway is not present, rely only on systemic pathway
- Higher Primates: PGF2a from the CL itself causes luteal regression, so no veno-arterial pathway needed
135
During menstruation, estrogen and progesterone levels _____, there is a loss of ____ support of the uterine lining, there is _____ of uterine blood vessels, and a ______ of the uterine lining.
- Decrease
- Hormonal
- Constriction
- Sloughing
136
What is a CIDR?
- Controlled Internal Drug Release
- Like an artificial CL
- Elevates progesterone, preventing estrus and ovulation (LH, FSH, and GnRH)
- Does not prevent luteal regression
- When the CIDR is removed, progesterone will drop, and in a few days the animal will enter estrus
137
Regu-Mate is _____. What does it do?
- Altrenogest
- It is an agonist of progesterone
- It is used in mares to either induce cyclicity when entering the breeding season, or to suppress undesired estrous behaviors
- It allows for scheduled breeding, because when you remove it, the mare enters estrus
138
Matrix is a _____. What does it do?
- Altrenogest
| - You can use it to synchronize estrus and parturition by giving it in sow feed.
139
What are three forms of artificial progesterone used to synchronize estrus?
- CIDR
- Regu-Mate
- Matrix
140
In primates, the CL produces ____ and _____.
- Progesterone
| - Estrogen
141
Describe birth control pills in humans.
- Contain estrogen to have negative feedback on GnRH and will stimulate reproductive tissues to simulate a normal cycle
- 21 days of normal pill, then 7 days of placebo for menstruation to take place
- Estrogen levels remain low because there is no dominant follicle
- GnRH, LH, and FSH remain low because estrogen inhibits the tonic center and progesterone inhibits the surge center
142
Why is prostaglandin given to farm animals? What must be considered in cattle?
- It causes luteal regression, synchronizing estrus
- In cattle, PGF2a will have no effect in days 0-6 of their cycle, so when it is given, only about 75% will be affected. Give again 10 days later to ensure all have CL regression.
143
Describe Ovsync strategies.
- Synchronize ovulation instead of estrus
- Allows you to breed by appointment
- Process: Give GnRH to cause the dominant follicle to ovulate and synchronize the onset of the next wave. After 7 days, give PGF2a which will cause the CL to regress. After 2 days, Give GnRH to cause the follicle that was selected after the first GnRH injection to ovulate. Then breed.
