Exam 2 Flashcards
Sry
activates cells within the gonads to produce testes determining factor
What develops first female or male tract
male tract
Anti-Mullerian Duct Hormone
regresses the female tract
What allows the wolfian duct in females to regress
absence of testorone
Male external genetalia growth
urethral groove grows and becomes the body of the penis, scrotal swelling and the phallus grows
Female external genetalia growth
the phallus shrinks and there is labial swelling
What causes homosexual behavior in cattle
high estrogen
Why don’t males need a surge center
once at a certain age they are constantly producing sperm cells as opposed to females who have a limited number of oocytes and need the surge to ovulate.
How does the surge center regress in males
It starts as indifferent
Then the testorone circulates and due to it being a small steroid it passes through the blood brain barrier
Then in the brain aromatase converts the testorone to estrogen
The high concentration of estrogen in the brain does not allow for growth of the surge center
Why doesn’t estrogen knock out the surge center in females
The females have alphafetal protein which binds to the estrogen in the body and because of the large protein size it can not go through the blood brain barrier
Sexual Dimorphism in the brain
The pre optic area is bigger in males than females as it helps them find mates
True hermaphrodites
both male and female internal and external genetalia
EX: some fish release both ova and sperm released from separate orifices and the fertilization is external
XY Genetic Pseudo-Hermaphrodite
Mixed internal tract, external female, the cells are not responsive testerone
XX Genetic Pseudo-Hermaphrodite
Ovary,, Mixed tract, external male, adrenal produces excess androgen
Freemartinism
both male and female tracts are present. Most commonly occurs in cattle
When does freemartinism most often occur
It occurs when cow has twins and one is a heifer calf and one is a bull calf. The bull calf develops normally and the female is the free Martin
How/Why does freemartinism occur in cattle
-The bull calf becomes a bull first, and the cows share placental blood until day 84. The reduced concentrations of AMH and androgens in the heifer calf from the blood of the bull calf causes the change in developing tract and start of sexual differentiation
Female sexual development in hyenas
-have an enlarged clitoris that resembles a penis
-nonfunctional vagina
-does not have an obvious phenotypic sex
How do female hyenas mate and give birth if they have a nonfunctional vagina
-mating occurs through the clitoris
-painful due to the small size that the fetus has to pass through
Why do female hyenas have these charecteristics
A lot of androgen production by the dam when pregnant and because of that there is natural virilization of the females in utero and changes how external genetalia forms
Puberty Definition
the time at which an animal becomes functionally capable of reproducing
Why can’t the age when behavioral traits are expressed not be an indicator of puberty in males
-can be influenced by other factors and can happen at a very young age
Why can’t the age at 1st ejaculation be an indicator of puberty in males
The first ejaculations often are
-not fertile
-only seminal plasma
-can not cause pregnancy
Why can’t when spermatozoa 1st appear in ejacualte not be an indicator of puberty in males
usually does not reach the critical threshold that would deem them functionally capable of producing
Why can’t when spermatozoa first appear in the urine be an indicator of puberty in males
it varies to much and leaking can occur at other times
What is defined as the indicator of puberty in males
age when ejaculate contains a threshold number of sperm (varies by species)
Why can’t the age of first estrus be an indicator of puberty in females
-usually no ovualtion occurs
-can happen as early as 2 months
-can simply be induced with estrogen
Why can’t the age of first ovulation be an indicator of puberty in females
-not fertile
-not easily detectable
-an developed hypothalamus, pituitary axis is needed to mature the ovary
What is defined as the indicator of puberty in females
age of reproductive competence
-time when production can be carried to term
-often defined by hormone levels
(progesterone)
HHLHHL
Why is it important to know the age of puberty in livestock
the early onset of puberty, the earlier get can become production ready.
Prepuberty in females
-Infrequent GnRH pulses
-Little follicle growth
-low estradiol
Hypothalamic control in female puberty
hypothalamus stimulate pituitary gland which then releases growth hormone which then causes the ovaries and testes to respond and produce sex hormones
Puberty in the female
-negative and positive feedback to estradiol is established
-follicular growth
-LH surge mechanism in place
What triggers puberty in females
estrogen coming from the ovaries, jump starts the surge to start puberty
Factors that influence puberty
-genetics (breed difference)
-Body weight (% body fat)
-Environment (seasons)
-Social Factors (male effect)
-Stress
Frisch Theory
A critical body fat and body weight are required for the onset of puberty
What did an experiment show with an increased plane of nutriton
It displayed an additional estrus prior to breeding
Spring Born Ewe Lambs
-reach puberty at 7 months
-less synchronously
-long day length programs the hypothalamus pituitary axis
Fall born ewe lambs
-puberty 12 months
-more synchronous
need to experience long day length to program the hypothalamus pituitary axis
Vandenburgh Effect
-male present=earlier onset of puberty
-females only=later onset of puberty
might be a way of regulating population density
Puberty in Humans
-growth spurt begins
(girls start earlier and are typically taller between ages 11-13)
-Full adult height
-reached about 3 years earlier in girls
Menarche
-first menstrual cycle
-typically occurs by age 12-13
-initally may involve anovulatory, irregular cycles
Spermarche
first ejaculation
-typically occurs by age 15
initial period of sterility
what hormone to follicles produce
estrogen
what hormone do corpus leuteum produce
progesteronw
Sign of standing heat in cows
cow that is standing to be mounted by another cow
Sign of standing heat in sheep
ewe turning head to tell the ram to come hither
Sign of standing heat in mares
display excessive uriniation and winking of the vagine
sign of standing heat in sows
Lordosis
applying pressure to the back causes them to stand
Hormone levels during estrus
estrogen is high and progesterone is low
Polyestrus
display estrus through the year
-cows,pigs,cats,mice and rats
Seasonally Polyestrus
display more than one estrous cycle during a specific time of year
Short day breeders
deer and sheep
-typically breed in the fall most come into estrus between September 1st and December 31st
Long day breeders
hamsters and horses
Melatonin and Breeding in short day breeders
-light goes down which stimulates the pineal gland which then releases melatonin
-the melatonin then raises GnRH and FSH and Lh
Monoestrus
displays estrus once a year
Why are rabbits an execption the rule
always half large amounts of follicles and do not have an estrus cycle
Spontaneous Ovulator
ovulates with a regular frequency and do not require copulation
Reflex (induced) Ovualtor
Ovulation induced only after stimulation of the vagina and/or cervix
-need a stimulus to ovulate
ex: rabbits, cats, ferrets, camels, llamas and alpacas
Follicular Phase
-Growth of Follicles
-dominant structure-preovulatory follicle
-dominant hormone is estradiol
starts with the regression of corpora lute and ends with ovulation
relatively short
Luteal Phase(description)
Growth of corpus lute (corpora lute)
-dominat structure-corpus luteum
-dominant hormone-progesterone
-starts with ovulation
-ends with luteal regression
Stages of the estrous cycle in the follicular phase
proestrus and estrus
Luteal Phase
metaestrus and diestrus
Proestrus
-increased estrogen secretion
-follicle growing
-progesterone decreasing
-due to cl regression
Estrus
-Sexual receptivity
-peak estrogen production
-LH and FSH surges
-Ovulation in mares and sows (since their estrus is fairly long)
Metaestrus
-increasing progesterone production
-formation of the CL following ovulation
-Ovulation in cows and ewes
-LH and estradiol is low
Diestrus
-Sustained progesterone production
-cl domination structure
-follicles continue to grow in waves
-shift in LH and FSH
-longest period of cycle
Cattle cycle length and duration of estrus
Estrus: 8-16H
Cycle length: 21 days
Sheep cycle length and duration of estrus
estrus: 24-36 hours
cycle length: 16 days
Goats cycle length and duration of estrus
estrus: 24-36 hours
cycle length: 21 days
Swine cycle length and duration of estrus
estrus: 48-72 houra
cycle length: 21 days
Horses cycle length and duration of estrus
estrus: 4-7 days
cycle length:21 days
What is observed that shows the menstrual cycle
the obervation of menses
What is observed that shows the estrous cycle
The observation of sexual receptivity (estrus)
How long is the length of the follicular and luteal phase of the menstrual cycle
it is half and half 50% luteal and 50% follicular
What three events are in the follicular phase of the menstrual cycle
-menstruation
-follicular growth
-ovulation
What three events are in the luteal phase of the menstrual cycle
-lutenization
-endometrial growth
-luteolysis
oogenesis
development of the oocyte
Zona Pellucida
assists fertilization and may provide protection
Vitelline membrane
surface layer of the oocyte
Cytoplasm(yolk)
contains many proteins, enzymes, nutrients, needed for survival of the zygote
Germinal Vesicle
nucleus containing genetic information
oogenesis
formation and development of the ovum
oogonium
the primordial cell which develops into the oocyte
oocyte
the early not yet fully developed ovum
ovum
the egg-the cell that is capable of developing into a new individual
oocyte formation
-primary oocytes formed from mitotic divisions of oogonia
-primary oocytes enter meiosis I
-become dormant
-maximum number formed during mid to late fetal life
What happens once max oocyte number is attained
actress and natural degeneration begins and continues for life.
oocyte development
-primary oocytes are surrounded by follicle cells in primordial follicles
-remain inactive
-follicle developes from primordial to primary (still not yet active)
What turns an oocyte into an ovum
fertilization when the sperm attaches to the oocyte
When does meiosis resume
only in preoculatory follicles
what activates meiosis to resume
LH surge
Number of fetal oocytes
2.700,00
Number of oocytes at birth
70,000
Number of oocytes at puberty
24,000
Folliculogenisis
classification and regulation of follicle growth
(starts talking once it is a tertiary follicle)
Granulosa Cells
-from cortex
-responsive to FSH
-convert testosterone to estradiol
Theca Cells
-from storm
-responsive to LG
-converts cholesterol to testorone
Components of follicular fluid
-Hormones
-Proteins
-enzymes
-carbohydrates
Functions of follicular fluid
-supports follicle growth
-aids in oocyte development and health
-mediates granulosa cell functions
Primordial Follicle
-single layer of squamous epithelial cells
-resting state
Primary Follicle
-single layer follicle cells
-primary oocyte but starts to expand
-follicle cells expand form squamous to cuboidal
-zona pellucida forms
Secondary Follicle
-primary oocyte (still in meiosis 1)
-multiple layers of granulosa cells
-thecal layer forms
-pre-antral
Early astral (tertiary) follicle
-primary oocyte which reaches maximum size
-grnaulosa cells expand
-antrum forms
-thecal layer more prominent
Graafian follicle (pre-ovulatory)
-last stage of tertiary follicle
-primary oocyte (oocyte still dormant)
What is follicular development stimulated and regulated by
-gonadotropins
-growth factors
-activin or inhibin (regulate FSH)
Follicular growth
-many are recruited to go from secondary stage to tertiary stage
-after that few are selected to grow
-one id selected (dominant)
First wave of follicular growth
-inovulatory
-progesterone is high
-the dominant follicle dies off and undergoes atresia
Second wave of follicular growth
-non-ovulatory
-during diestrus
-follicle becomes dominant but then undergoes atresia
-happens right before luteolysis
Ovulatory Wave of follicular growth
-since corpus leutem has died follicle is able to produce more and more estrogen
- this allows the dominant follicle to grow and then ovulate
FSH Follicle growth
-granulosa cell mitosis
-increases lh receptors
-steroidogenesis
-effects prenatal and antral follicles
LH Follicle growth
-only impacts astral follicles
-surge starts ovulation
-resumption of meiosis-oocyte
What inhibits follicle growth
presence of a dominant follicle
-inadequate production of gonadotropins
-steroids
(estrogens and androgens)
-inhibin
Inhibin
protein produced by follicles which inhibits other follicles from developing FSH release
Recruitment stage
-entry into gonadotropin sensitive pool
-dependent on FSH
Selection Stage
-more dependent on LH
-inhibin present to stop the FSH
-ovulatory follicles emerge
Dominance stage
final growth of ovulatory follicle and inhibition of others
What would you do if you were a producer and wanted to increase the number of ova produced by your prized cow
you would give a lot of fish during a critical stage which would prevent the follicle from undergoing apoptosis
Ovulation stimuli
LH surge
Ovulation specific cascade of events
-degredation fo follicle wall
-extrusion of oocyte
collapse of follicle
Changes in oocyte
Gap junction breakdown between granules cells and oocyte
then
removal of meiotic inhibition
then
first polar body
then
haploid oocyte
then
fertilization
Changes in follicle caused by pge2
-blood flow to every dominant follicle
then edema
then follicle pressure
changes in follicle caused by pgf2a
-contraction of ovarian smooth muscle and release of lysomal enzymes
which then causes follicular pressure and the follicle wall to weaken
changes in follicle caused by shift from E2 to P4 by dominant follicle
-raise in progesterone which then causes a release of collagenase then the follicle wall weakens
Lutenization
-priocess that transforms the granulosa and theca cells into luteal cells (terminal deviation)
-triggered by surge of LH
-causes profound changes in the follicles that become corpora lute
Number of luteal cells
-Large cells undergo hypertrophy (3 fold)
- Small cells undergo hyperplasia (5 fold)
Vascularization of CL
-Initiated by angiogenic
factors from follicle
-Vascularity effects CL steroid synthesis and delivery of hormones
Insufficient CL Function
Failure to maintain luteal phase and/or pregnancy
Important in domestic animals
`Actions of Progesterone
- Reduces GnRH pulse amplitude & frequency
- Prevents behavioral Estrus
- Stops the preovulatory LH surge
- Reduces myometrial tone
- Stimulates endometrial gland development and secretion
- Stimulates aveolar development in mammary gland
Luteotropic hormons in humans
LH
Luteotropic hormons in sheep, cows and mares
LH
Luteotropic hormons in pseudopregant rabbits
estradiol and LH
Luteotropic hormons in pseudopregnat rats and mice
prolactin, LH and estradiol
How to use progesterone as a diagnostic tool
Recommend sampling 3 times over 21 days
Serum concentration of >1ng/ml = Cycling
What does this progesterone levels say : L-L-L
not cycling, (prepubertal or anestrus), cystic
What does this progesterone levels say : H-H-H
not cycling possibly pregnant
What does this progesterone levels say : H-H-L
cycling
-in estrus
-recently ovulated
What does this progesterone levels say : H-L-H
-cycling
-early luteal phase
-ovulated 5-7 days ago
Luteolytic agents
Any of a
factor that can reduce luteal progesterone
hormone.synthesis or secretion and/or prevent the action
luteotrophic
What stimulated luteal regression
-prostaglandin PGF2a secreted by uterus
-exits via veins
-counter current exchange to ovarian artery
Is the ovarian cycle of ruminant uterine dependent
yes! with no uterus the cl does not regress for almost the entire gestation length
Luteolysis in the primate
-does not require the uterus
-cl lifespan in the human is 12-14 days unless pregnancy occurs
-in the absence of pregnancy the cl self destructuts
When is the cl not sensitive to PGF@a
-in cattle and sheep 1-7 days
-in swine 1-12 days
functional regression
process by which the corpus lute loses its capacity to synthesize and secrete progesterone
structural regression
process by which the corpus lute undergoes structural involution
Luteolysis physiological effects
- Decreased blood flow
- Cellular response
- ↓ Progesterone synthesis
Apoptosis
-* Immune response
-increase in lymphocytes and macrophages
Rathke’s pouch develops into which reproductive tissue?
anterior pituatary
T or F The majority of reproductive hormones circulate at milligram levels in the blood and body tissues.
False
Which hormone stimulates surge of luteinizing hormone during the time of sexual receptivity?
estradiol
You are currently editing a video that shows the development of the anterior pituitary. Unfortunately, the video files are not in order and you need to place these in the correct order. Below are the file names. Place these in the correct order.
1. Rathke’s pouch wraps around posterior pituitary
2. Stalk of Rathke’s pouch regresses
3. Bone encloses anterior pituitary
4. Oral portion of mouth starts to reach for infundibulum
5. Infundibulum and Rathke’s pouch touch
4, 5, 2, 1, 3
You have a goat with an XY genotype but you were able to knock out the gene for AMH when the goat was a 2-cell embryo so AMH could no longer be made. When this goat develops, what kind of duct systems will it have from a reproductive standpoint?
wolfing and mullerin ducts
You are a cattle veterinarian and you are asked to determine the sex of a calf in utero at 2 months (60 days) of gestation. You ultrasound the pregnant cow and determine that the calf in utero is a male. What structure did you see on the ultrasound that allowed you to determine the calf’s sex?
scrotum
If you were able to knock out alpha-fetoprotein in the circulation a developing female fetus. The hypothalamus of that offspring at birth would have…
a tonic center
Stephanie and her husband, Mark, have been trying to get pregnant for years, but have not been successful. Frustrated with this, the unhappy couple visited a doctor and the doctor suggested to do a karyotype on Stephanie and Mark. Stephanie’s sex chromosomes are XY and Mark’s are also XY. Why can they not get pregnant?
Stephanie is a pseudo-hermaphrodite
BOGO is a cow known for having twins on Makin’ Jerky Farms. BOGO recently had twins, a male and a female, and the owner would like to keep the female for future stock. What is faulty about the owner’s logic?
The female twin is likely a freemartin and cannot become pregnant
which statement is correct
a.
The presence of a boar will prevent gilts from reaching sexual maturation.
b.
Minimal follicular growth occurs during the luteal phase prior to puberty.
c.
The period of sexually receptivity, known as estrus, can be easily observed during a primate’s estrous cycle.
d.
The cow and mare ovulate while in estrus whereas the sow and ewe ovulate during metaestrus.
e.
All estrous cycles have a follicular and luteal phase but the frequency of observed estrus is species independent.
All estrous cycles have a follicular and luteal phase but the frequency of observed estrus is species independent
True or False. Progesterone induces gonadotropin releasing hormone pulse amplitude and frequency during sexual maturation.
False
True or False. The traditional domestic livestock species (cattle, sheep, and hogs) have a delayed onset of puberty compared to members of the Camelidae family.
False
What is the correct order of the following stages within the estrous cycle following luteal regression?
Proestrus, Estrus, Metaestrus, Diestrus
Which which of the following scenario(s) would likely result in a delay of menarche?
A girl that is more than 30% underweight
b.
An Olympic gymnast who has less than 8% body fat
c.
A girl that has been categorized as obese
d.
A and B
A and B
You have discovered a new species of anole on the island of Fantastica. Through observation of tissues of anoles that have died, you determined that this species has both male and female sexes with XY and XX chromosomes, respectively. You also observe that there is a 1:10 ratio of female to males on the island. What is the most likely explanation for this sex ratio?
Hot temperatures during egg incubation have affected the sex ratio
Activation of the ___________________ initiates onset of puberty.
hypothalamus
A seasonally polyestrus spontaneous ovulating species is
a fox, a mare, a sheep, a cat, a pig
You made a power point for your reproductive physiology class of the sequence of the menstrual cycle. Unfortunately your mischievous cat, Butch Catsidy, decided to lay on your keyboard and this rearranged your slides. You need to rearrange it into the correct order again. What was it?
a.
Menstruation, Follicular Growth, Luteinization, Ovulation, Endometrial Growth, Luteolysis
b.
Menstruation, Follicular Growth, Ovulation, Luteinization, Endometrial Growth, Luteolysis
c.
Menstruation, Follicular Growth, Endometrial Growth, Ovulation, Luteinization, Luteolysis
d.
Menstruation, Luteinization, Ovulation, Endometrial Growth, Follicular Growth, Luteolysis
e.
Menstruation, Ovulation, Lutenization, Endometrial Growth, Follicular Growth, Luteolysis
Menstruation, Follicular Growth, Ovulation, Luteinization, Endometrial Growth, Luteolysis
At No Goats No Glory Farm you would like to do a blood test to see what part of the estrous cycle your does are at. The blood test comes back stating that luteinizing hormone is high, follicle stimulating hormone is high, estrogen is high, and progesterone is low. What stage are your does in?
Follicular Phase: Estrus
At La La Lamb Farms you have a new manager that has never managed sheep, but has managed horses. The new manager states he plans to start breeding this spring or summer and he will check every 5-7 days for signs of estrus. What is wrong with the new manager’s plan?
a.
Sheep are short day breeders
b.
Sheep should be checked at least once a day if not twice a day
c.
He is using a horse protoc
a and b
What is required for the onset of puberty?
Reaching a critical body weight and body fat amount
Which enzyme is responsible for converting pregnenolone to progesterone?
3beta-hydroxysteroid dehydrogenase
While looking at a graph that shows estrogen concentrations during a heifer estrous cycle, your roommate notices that although estrogen is basically low, there are 2 little bumps, one around Day 9 of the cycle and one around Day 15 of the cycle . She asked you what was causing these bumps? How did you respond?
They are from dominant follicles.
At No Goats No Glory Farm you would like to do a blood test to see what part of the estrous cycle your does are at. The blood test comes back stating that luteinizing hormone is low, follicle stimulating hormone is low, estrogen is low, and progesterone is low. What stage are your does in?
Luteal Phase: Metestrus
Goats are classified as seasonally polyestrous with spontaneous ovulation.
true
At No Goats No Glory Farm you would like to do a blood test to see what part of the estrous cycle your does are at. The blood test comes back stating that luteinizing hormone is low, follicle stimulating hormone is low, estrogen is low, and progesterone is high. What stage are your does in?
Luteal Phase: Diestrus
