Quiz 4 Flashcards
3 Steps of Parturition
- Preparatory
- Expulsion
- Cleaning
In step one of Parturition (preparatory), what is happening?
- E2 increases
- P4 decreases
- Relaxation of cervix
- Contractions
- Lubrication increases
- Oxytocin increases
In step two of Parturition (expulsion), what is happening?
- Strong, rhythmic contractions
- Chorio-allantoic rupture - ends with fetus in birth canal
- Amnion rupture
In step three of Parturition (cleaning), what is happening?
- Accommodates delivery
- Detachment/expulsion of placenta/membranes
Descrive post-partum.
- Involution (not highly correlated to fertility)
- “Gets things back to normal”
Mice have a _____ pregnancy - meaning they are practically pregnant again during their _____.
21 day; involution
What does dystocia mean?
“Difficult birth”
What are common causes of dystocia?
- Size of the fetus
- Placement/Orientation
- *Higher incidence in twins
What is a freemartin pregnancy?
- When a cow gives birth to twins (M & F) and the M affects the F
- (Ex: Twin F born without ovaries –> infertile)
Why is a C-section termed Caesarian?
Caesar thought his kin was too good to be born vaginally
A cow and sow need ______ for majority of pregnancy.
Corpus luteum
Human placenta starts to produce _____
CRH
What are surfactants?
Premature babies that need to be given cortisol
Secreted by the ovary and/or placenta depending on the species
Relaxin
Neuro-endocrine H/P/A complex (FETAL)
Hypothalamus
to (CRH)
Anterior Pituitary
to (ACTH)
Adrenal
to (Cortisol)
Placenta
(Increase PGF2alpha and E2, Decrease P4)
Gonadostat Hypothesis - year proposed?
1930
What does the gonadostat hypothesis propose?
Puberty occurs due to a resetting of H/P/G and how feedback occurs
When you castrate, what hormone accumulates/increases?
LH
Surge and Pulse are controlled by different parts of the _____.
Hypothalamus
Pulse frequency refers to _____, while pulse amplitude refers to _____.
Pulse frequency - time
Pulse amplitude - height
Bull puberty =
38 weeks
Young animals will have _____ as they are developing.
Increase in LH
Radioimmunoassays:
Antibody?
Antigen?
Antibody - LHAb
Antigen - LH-Iodine I^125
Can measure how much is in the blood using radio wave markings
Before puberty (males), testosterone is produced but…
Not enough to have spermatogenesis
In males, there is a stronger (-) feedback until _____. Then feedback _____.
Until puberty
Then feedback amount relaxes
H/P/G of Female
Hypothalamus
to (GnRH) (+)
Pituitary
to (FSH, LH) (+)
Follicle
E2 (-) Feedback goes back to both Pit and Hyp
H/P/G of Male
Hypothalamus
to (GnRH) (+)
Pituitary
to (FSH, LH) (+)
Testis
Testosterone (-) Feedback goes back to both Pit and Hyp
Gonadal Maturation
Seminiferous tubules produce sperm
Behavioral Maturation
In the brain
*Progression, not one specific event
What are permissive signals?
Metabolic status, photoperiod, demographics, sex ratios
Developmental clock
H/P/G Axis maturation
Heifer puberty?
10-12 mo
In a heifer, if there is high grain intake, then puberty occurs _____. Around what age?
Earlier
8 months
In a heifer, if there is low grain intake, then puberty occurs _____. Around what age?
Later
14 months
What is the developmental clock?
- Changing of the H/P/G Axis
- Change in sensitivity to feedback
- Pre-puberty some estradiol or testosterone has a high effect
- Hypothalamus: surge center
- Responds to LH surge to cause ovulation (females only)
- Tonic center: pulsatile LH - estrus cycle
- Male & female
- Pulse frequency and amplitude
Pulse amplitude and frequency are controlled by _____ at hypothalamus.
GnRH
Pulse GnRH leads to…
Pulse LH
Types of permissive signals
- Metabolic: Heifers/Body weight
- Social grouping: Can influence time of puberty
- Pheromones
- Photoperiod: Affects time its going to breed
Tonic Center
Pulse Frequency
Pulse Amplitude
During the cycle, estradiol has a modest affect on _____.
Amplitude
Progesterone has a high/large affect on _____.
Frequency
In anestrus
E2 and P4
Both have a strong affect on frequency
Decrease pulse frequency
Photoperiod
Stimulation to light receptors in the retina
Sex Determination (3)
1) Chromosome
Humans: 44 autosomes, 2 sex chromosomes; 46 total
2) Temperature
Crocodile and some fish
3) Sex Change
Fish, snail, clam: Dominant is female, rest are male
XXY
Klinefelters
Extra X chromosome
Most common proble, reduced fertility, hypogonads
XXX
Trisomy X
Reproductive, not normally diagnosed
XYY
Not normally diagnosed
XO
- Turner’s Syndrome
- Sterile and lots of problems
Alpha-fetoprotein
Prevents estridiol from entering the brain
Would be masculinized if entered
Day 0
Genetic cells
not differentiated
Y present or not
Day 17/18
Rudimentary Nervous System
Rudimentary GI Tract
Rudimentary Cardiovascular System
Rudimentary Urinary Tract
Undifferentiated gonad
Day 28
Gonadal Migration
Male: Wollfrian Ducts
Female: Mullerian Ducts
Differentiated, sex specific
Day 55
Male: Vas defferines and seminierous tubules
Female: Oviduct and uterus
In abdominal cavity
Day 80
Testis still in abdominal cavity but moving lower
External Genitalia
Indifferent/ Bipotential
1) Genital Fold
2) Genital Swelling
3) Genital Tubercle
In males, Sry is considered the testis dominating factor. Sry will activate…
SF1
During sexual differentiation in males, fetal leydig cells secrete testosterone. This testosterone induces degeneration of the Mullerian ducts. T or F
F
Name the 3 components that make up the indifferent external genitalia.
- Genital swelling
- Genital tubercle
- Genital fold
Puberty occurs in gilts around _____.
28 weeks of age
If no males are present in a gilt herd, when will they reach puberty?
32 weeks of age
Name two permissive signals that can affect the onset of puberty in female swine.
- Presence of male
- Metabolic changes
In social groupings, if you have 10 gilts at what age will they reach puberty?
28 weeks
In social groupings, if you have 3 gilts at what age will they reach puberty?
32 weeks
In social groupings, if you have males present at what age will they reach puberty?
24 weeks
What is the gestation of a ewe?
Ewe (short day breeders) - Gestation 147 days / 5 months
In the ewe, parturition occurs in response to activation of the maternal hypothalamic/pituitary/gonadal axis. T or F
False
At parturition in the ewe, what causes the release of oxytocin from the maternal posterior pituitary?
Pressure sensors in the cervix
Puberty in the ewe lamb can occur as early as 5-6 mo of age. Farmer Bob in southern KY had his ewes lamb last October. When should he expect these ewe lambs to reach puberty?
These ewe lambs should reach puberty this October. This is because they missed the photoperiod the October they were born so they did not go into puberty since they would not be breeding.
Short-day breeders: need photoperiod
11-12 months of age; next breeding period
What gland produces the hormone melatonin?
Pineal gland
Retina –> Superior cervical ganglion –> Pineal gland –> melatonin –> hypothalamus –> GnRH
Farmer Bob’s cousin Billy decided to raise swine. He purchased 20 infant gilts and one mature boar to start his operation. They were all housed in close proximity to each other. Puberty typically occurs in gilts around 28 weeks of age. At what age should Billy expect his 20 gilts to reach puberty?
24 weeks of age due to the presence of the mature boar
In the ewe, estradiol and progesterone exert negative feedback on the H/P/G axis. During periods of anestrus, what is the effect of:
a. ) estradiol
b. ) progesterone
on the pattern of secretion (pulse amplitude and/or pulse frequency) of LH?
E2 and P4 decrease pulse frequency during anestrus.
During estrus cycle, what effect does estradiol and progesterone have on the pattern of secretion (pulse amplitude and/or pulse frequency) of LH?
During the cycle, estradiol affects pulse amplitude. Progesterone affects pulse frequency.
In males, SRY is considered the testis determining factor. Sry will activate:
SF1
Men typically have 44 autosomes plus 2 sex chromosomes (XY). When a male is born with an additional Y chromosome (ex: XYY, a sex chromosome aneuploidy), it is expected that he will be of normal fertility. T or F
True
During sexual differentiation in males, fetal leydig cells secrete testosterone. This testosterone induces degeneration of the Mullerian ducts. T or F
False - Wolferian
During sexual differentiation, what cells produce anti-mullerian hormone?
Sertoli cell
The male prenatal brain is masculinized by _____.
Estradiol
Describe the role of alpha-fetoprotein with respect to prenatal brain development.
Alpha-fetoprotein prevents estradiol from reaching the brain in a female. If estradiol was to reach the brain, the brain would be masculinized.