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1
Q

Write brief notes on the following topics.

SEX DIFFERENTIATION

A

Sex differentiation:

  • 4 steps:
    - Chromosomal (genetic)
    - Gonadal (hormonal)
    - Somatic (phenotypic)
    - Psychic (brain)
    - chromosomal:
    - mammals xx & xy
    - birds zw(female) & zz
    - Some reptiles have no heteromorphic sex chromosomes
    - temperature determines sex in many reptiles (pivotal temp)
    - TDF
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2
Q

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SEMINAL PLASMA

A

sperm +seminal plasma = semen

ejaculated sperm delivered to female repro tract via seminal plasma

Seminal plasma derived from accessory glands
–Prostate gland
–Seminal vesicle
–ampulla

Produced by accessory sex glands
Varies widely between species
Provides a fluid vehicle for sperm (buffer and
metabolic support)

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3
Q

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RAM EFFECT

A
  • synchronised oestrus cycle
  • cycling approx 2- 3 months earlier (from mid Dec to late October)
  • sheep are short day breeders
  • works best close to anticipated breeding season
  • melatonin works best with ram effect
  • progesterone injection to prime females - avoids short cycle
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4
Q

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REGUMATE

A
  • supresses oestrus in mares
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5
Q

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LEYDIG CELLS

A
  • primary source of testosterone and androgen in males
  • ## in the testes (between seminiferous tubules)
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6
Q

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INDUCTION OF PARTURITION

A

Stage 1: Initiation of myometrial contractions

  • regular uterine contractions
  • P4 converted to E2
  • pressure on cervix = oxytocin from pituatry
  • Placenta produces PGF2α

Stage 2: Expulsion of the fetus

  • Strong uterine and abdominal contractions
  • Relaxin loosens supportive tissue of the birth canal
  • cervix and vagina produce mucus
  • Fetal movement promotes further myometrial contraction

Stage 3: Expulsion of the fetal membranes

  • uterine contractions decrease
  • Vasoconstriction of vessels at fetal/maternal interface
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7
Q

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SPERM SEXING

A
  • differentiates based on x and y DNA content
  • stained and the separated with a lazer
  • used in cattle
  • currently researching to use in sheep
    Benefits:
  • female selection: replacement of dairy heifers and stopping unwanted male calves
  • male selection: desirable genes –> increased stud production
  • manage endangered species breeding in captivity
  • control sex-linked diseases in humans
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8
Q

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PUBERTY

A

Puberty – “the period or age at which a person is first capable of sexual reproduction of offspring”
• animal gains ability to produce offspring
• Requires physiological, physical and behavioural maturation
• Not a dramatic event; can take months - years.

  • indicators of puberty in males and females
  • puberty initiated by Influence of the pineal gland and melatonin
  • different factors affect puberty

Immediately before puberty starts:
• Pituitary contains Gn’s but they are not secreted in large quantities
• Peaks of Gn’s gradually increase closer to puberty
• Follicles develop and secrete low levels of E2 but ovulation does not occur
• Low level spermatogenesis may occur

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9
Q

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GnRH PULSE GENERATOR

A

located in hypothalamus

Elicit release of FSH and LH from the anterior pituitary gland, which in turn stimulate release of steroid from the testes

melatonin stimulates GnRH secretion

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10
Q

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MORULA

A
  • say 3-4 after oocyte fertilised

Morula Compaction:
– Occurs at around 16- to 32-cell stage
– Tight junctions form between outer cells
– Individual cells become less distinct
– Cells merge into an “amorphous mass”
– Sodium is pumped into the interior, creating an osmotic gradient
– This causes water to enter the embryo

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11
Q

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LORDOSIS

A

Lordosis = curving of the spine

  • a visual cue of errection
  • mice/ rats/ cats/ rabbits assume lordosis as a mating behaviour
  • response of increased estrogen
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12
Q

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EPIDIDYMIS

A

• Mature and store sperm

– Sperm subsequently transported by muscles in epididymis
– Passage through epididymis takes 6-14 days
Maturation of sperm through epididymis:
- Caput (head): Sperm immotile, infertile, Proximal cytoplasmic droplet
- Cauda (tail): Sperm forward progressive motile, Fertile, Distal cytoplasmic droplet

Sperm require further maturation in the epididymis and inside the female tract before fertilisation

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13
Q

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BEHAVIOURAL OESTRUS

A 
- mating behaviour --> changes depending on species
Rats:
Pre-copulatory
• Genital sniffing
• Display of “ear quiver response”
Copulatory
• Assumes lordosis position
Post-copulatory
• Genital licking

Horses:
Pre-copulatory
• Frequent urination
• Tail deviation (exposure of genitals)
• Winking
• Genital sniffing
Copulatory
• Acceptance of male
Post-copulatory
• Minimal
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14
Q

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FOLLICULAR WAVES

A

Lecture notes, oestrus cycle
(slide 16)

First, second and 3rd waves

Continuous follicular waves give constant high E2

In Proestrus: P4 decreasing, E2, LH and FSH increasing with FSH suddnly dropping at end of prestrus

In estrus: E2 reaches a peak and LH spikes, FSH comes back up to its highest point. ALL 3 decrease rapidly at end of estrus phase

  • length of follicular phase variable between species
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15
Q

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JUVENILE IN VITRO EMBRYO TRANSFER

A

WHY?
To increase the rate of genetic gain by decreasing generation interval

HOW?
♀Prime juvenile animals at a time to capture the follicular development,
cause ovulation and collect ova
♂Initiate spermatogenesis and collect sperm by testicular biopsy or castration

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16
Q

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GnRH PULSES

A 
GnRH pulses elicit release of
FSH and LH from the anterior
pituitary gland, which in turn
stimulate release of steroid
from the testes
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17
Q

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OOCYTE MATURATION

A

– In primordial and pre-antral follicles
– Oocyte diameter increases from 25 µm to 130 μm
– Zona pellucida (protein coat) formed
• Gap junctions maintain link between oocyte and the surrounding cells
– Cytoplasmic changes
• Large amounts of rRNA and mRNA synthesized
• Essential proteins accumulated
• Organelles formed (mitochondria, ER, Golgi complex)
– In antral follicles
– Oocyte diameter doesn’t increase further
– Protein accumulation and mRNA synthesis continues
– Surrounding cells promote oocyte maturation

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18
Q

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BLASTOCYST

A

5-6 days after ovulation

approx 70-100 cells

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19
Q

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MATERNAL RECOGNITION OF PREGNANCY

A

Conceptus provides a biochemical signal that prevents luteolysis (maternal recog of pregnancy)

different in different breeds
PGF2a blocked in all species but pigs

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20
Q

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SEX DETERMINATION

A

Mammals
xx(female) xy(male

Birds
females (zw)
males (zz)

reptiles
some have no heteromorphic sex chromosomes

temp determines sex in many reptiles

TDF

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21
Q

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ABNORMAL SEXUAL DIFFERENTIATION

A

androgen recpertor deficency
adrenal hyperplasia in XX females
Congenital adrenal hyperplasia in XY males
progestational steroids during pregnancy

XX males
freemartism in cattle

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22
Q

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SPERMATIDS

A

an immature male sex cell formed from a spermatocyte, which may develop into a spermatozoon without further division.

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23
Q

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PMSG

A

Pregnant Mare Serum Gonadotrophin or eCG

  • can be used for moderate stimulation of ovulation
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24
Q

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MELATONIN

A

from pineal gland releases melatonin which acts on hypothalamus supre-chiasmatic nucleus –> GnRH pulse generator

increases twinning rate (in lambs)
advances breeding season

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25
Write brief notes on the following topics. | OVASTIM
fecundity (fertility) vaccine that increases the eggs available for fertilisation by the ram, increasing twinning rates
26
Write brief notes on the following topics. | FEMALE SENESENCE
 Human female senescence is abrupt – depletion of eggs  Farm animals is reduced ability of ovaries and uterus to support pregnancy (unusual, as animal disposed of prior to this occurring) embryo survival decreases
27
Write brief notes on the following topics. | PREIMPLANATION EMBRYO DEVELOPMENT
ootid --> zygote --> 2 celled embryo --> morula --> early blastocyst --> hatching blastocysts --> hatched blastocyst
28
Write brief notes on the following topics. | EXTRAEMBRYORIC MEMBRANES
chorion and amnion There are 4 - They are the YOLK SAC, the ALLANTOIS, the AMNION, and the CHORION
29
Write brief notes on the following topics. | CLONING
creating an animal that is genetically identical to a donor animal through somatic cell nuclear transfer
30
Write brief notes on the following topics. | CRYOPROTECTANTS
pellets and straws | – Cryopreserved sperm require more sperm per dose due to having half the lifespan of fresh sperm
31
Write brief notes on the following topics. | METHODS OF SEXUAL CONGRESS
 Incorporation  Separation  Alternation
32
Write brief notes on the following topics. | BEHAVIOURAL OESTRUS
a phrase used to describe the timeframe in which female animals are most receptive to sexual behaviors express behavioural signs of oestrus
33
Write brief notes on the following topics. | SENESCENCE
Senescence – “growing old; aging” Issues with reproducing in this phase
34
Write brief notes on the following topics. | SPERMATOGONIA
an undifferentiated male germ cell
35
Write brief notes on the following topics. | SERTOLI CELLS
somatic cells of the testis that are essential for testis formation and spermatogenesis
36
Write brief notes on the following topics. | BLOCK TO POLYSPERMY
the zona pellucida, a structure that surrounds mammalian eggs, becomes impermeable upon fertilization, preventing the entry of further sperm
37
Write brief notes on the following topics. | EMBRYO MORTALITY
``` - Vast majority of losses occur at early embryo stages – ~30% of all fertilised oocytes perish before day 35 – Embryo developmental arrest – Implantation failure – Very few losses occur after day 35 when attachment is complete ```
38
Write brief notes on the following topics. | PREGNANCY DIAGNOSIS
Ram harnesses | ultrasound
39
Write brief notes on the following topics. | ADOLECENSE
increased reproductive activity
40
Write brief notes on the following topics. | GnRH AGONISTS
Two weeks pre-treatment with GnRH agonist suppresses follicle development ``` GnRH agonists (long acting) decrease gonadotrophin secretion in most species (down regulation of receptors) ```
41
Write brief notes on the following topics. | R STRATERGISTS
* Small body size * Short lifespan * Short gestation * Large litter * Rapid rate of development * Short birth interval * Variable popn size e.g. rodents
42
Write brief notes on the following topics. | PROSTOGLANDIN
• Prostaglandin F2α secretion increases during parturition Causes deterioration of cervical mucus used to synchronise oestrus
43
Write brief notes on the following topics. | FSH
Follicular stimulating hormone acts on sertoli cells FSH and LH required to initiate spermatogenesis granulosa cells --> Responds to FSH to produce oestrogen, inhibin and follicular fluid • Repeat injections of GnRH to stimulate FSH/LH activity (to manipulate breeding season) FSH action early in diestrus may produce a mid-cycle follicle that will sometimes ovulate, but more usually regresses
44
Write brief notes on the following topics. | CHORIONIC GONADOTROPHINS
hCG a hormone produced by the placenta during pregnancy. It helps thicken a person's uterine lining to support a growing embryo and tells the body to stop menstruation
45
Write brief notes on the following topics. | REPRODUTIVE SENILITY IN MALE MAMMALS
• Males generally fertile until death – continue to produce spermatozoa but fertility does decline BUT • May become physically incapacitated and unable to mount • There is a gradual decline in sexual interest from peri-pubertal stage
46
Write brief notes on the following topics. | OXYTOCIN
increase during parturition Stimulates muscular contractions --> sperm transport in ejaculation Oxytocin, sympathetic controlled contraction of smooth muscle
47
Write brief notes on the following topics. | PHEROMONES
attract over a considerable distance social factors --> caused by pheromones in saliva, urine and sweat
48
Write brief notes on the following topics. | PROSTATE GLAND
– Seminal plasma derived from accessory glands – Prostate gland role: produce the fluid that nourishes and transports sperm (seminal fluid)
49
Write brief notes on the following topics. | INTRAUTERINE INSEMINATION
sperm is placed directly into the uterus using a small catheter
50
Write brief notes on the following topics. | CONGRUENCE OF BRAIN (BEHAVIOURAL) SEX AND PHENOTYPIC SEX
Hormonal and Phenotypic Sex Males  Presence of TDF, AMH and testosterone  Wolffian ducts form epididymis, vas deferens and accessory sex glands  Penis and scrotum develop Females  Absence of TDF, AMH and testosterone  Müllerian ducts form oviducts, uterus, cervix and cranial vagina  Clitoris, labia and vagina develop Brain Sex  Exposure of fetus to sex hormones alters brain structure and function  Affects adult sexual behaviour  Examples  In rats, brain of newborn female masculinized by 17β-oestradiol  In sheep, female fetus exposed to androgens fails to respond to LH in later life ``` Genotypic vs. Phenotypic Sex  Genotypic (chromosomal) sex  X + X = female  X + Y = male  Phenotypic (hormonal) sex  What happens when hormone levels aren’t right during fetal development? ```
51
Write brief notes on the following topics. | PENILE ERECTION MECHANISMS
``` psychogenic stimuli (visual cues, sniffing, pheromones) Nervous Stimulation (tactile stimulation, olfactory cues) ``` Erection – Parasympathetic neurons fire, release NO from terminals, activates enzyme • Causes arterial dilation and increased blood flow into corpus cavernosa • Intracorporal pressure increases, compressing emissary venules; blood ‘trapped’ – Relaxation of the retractor penis muscle –Straightening of the sigmoid flexure
52
Write brief notes on the following topics. | ENDOCRINE CONTROL OF TESTES
The hypothalamus and pituitary gland control how much testosterone the testes produce and secrete.
53
Write brief notes on the following topics. | SEMINAL VESICLES
glands that produce the fluids that will turn into semen
54
Write brief notes on the following topics. | BEHAVIOURAL SEX
``` Female sex behaviour • Maternal behaviour • Mammary glands • Vaginal mucus • Uterus • Odour ``` ``` Male sexual behaviour • Aggressive behaviour • Horns or Antlers • Neck musculature • Mane • Odour ```
55
Write brief notes on the following topics. | SPERMIOGENESIS
the process by which haploid round spermatids complete an extraordinary series of events to become streamlined spermatozoa capable of motility 1. mitotic proliferation 2. meitoic division 3. cytodifferentiation (spermatogenesis) different sperm initiate division at diff times. - sperm going through school to graduation (gonia --> cyte --> cyte --> tid) RATE OF SPERMATOGENESIS IS CONSTANT
56
Write brief notes on the following topics. | EMBRYO SPLITTING
Zona then splits at the weakest point – Part of the embryo herniates through the hole in the zona – Embryo completely sheds zona as split widens monozygotic conjoined twins embryo doesn't split completely What causes embryo splitting? Several factors for causes of embryo splitting were suggested, including maternal age, prolonged embryo culture, ovarian stimulation, and zona pellucida (ZP) manipulation the formation of twins or multiples through artificial microsurgical splitting of an embryo at the cleavage or blastocyst stage
57
Write brief notes on the following topics. | PERINATAL MORTALITY
deaths commencing from at least 20 weeks gestation
58
Write brief notes on the following topics. | ACROSOME
head of sperm | contains enzymes required to get into egg (penetrate zona pellucida)
59
Write brief notes on the following topics. | TERMINAL BREEDERS
Individuals breed then die eg salmon
60
Write brief notes on the following topics. | COLD SHOCK SPERM
When sperm cells are cooled too fast to 5°C, they undergo irreversible damage called cold shock. The damage to the sperm cells is caused by changes in the plasma membrane as it is cooled.
61
Write brief notes on the following topics. | SPERM MOTILITY ASSESSMENT
sperm movement - how active they are | damage to sperm
62
Write brief notes on the following topics. | OESTROGENS
Oestrogens (E2; behaviour) Dominated by oestrogen which • Triggers LH surge • Stimulates oestrous behaviour • Prepares female tract for sperm and ovum transport and fertilisation
63
Write brief notes on the following topics. | CHORION
the outermost membrane around the embryo
64
Write brief notes on the following topics. | SERTOLI CELLS
somatic cells of the testis that are essential for testis formation and spermatogenesis.
65
Write brief notes on the following topics. | THERMOREGULATION OF TESTES
The tunica dartos, a thin sheet of smooth muscle under the scrotal skin, is controlled by sympathetic nerves and contracts and relaxes in cold and warm environments, respectively. The cremaster muscle also contracts to draw the testes closer to the body under cold ambient conditions
66
Write brief notes on the following topics. | FOLLICULAR DOMINANCE
Superovulation is more effective if the female is in the luteal or early follicular phase Presence of a dominant follicle can override the effect of FSH
67
Write brief notes on the following topics. | QUASI COPULATION
No female penetration but attempt at close deposition of gametes. eg • Frogs
68
Write brief notes on the following topics. | TWINS
– Monozygotic twinning – “Identical” twins • Genetically identical, same sex – Derived from the same embryo (one oocyte and one sperm) – Dizygotic twinning – “Fraternal” twins • Can be same sex or opposite sexes – Two oocytes fertilised separately by two sperm Cows – Dairy breeds 3.5%, beef breeds <1% – Calf survival not reduced – Chorioallantois of conceptuses fuses causing freemartinism Ewes – Some breeds are highly prolific eg. Finnsheep, Booroola Mares – Thoroughbreds 1-2%, draft-type 3% – Fetuses prone to abortion, mummification or neonatal death
69
Write brief notes on the following topics. | GRANULOSA CELLS
supporting the developing oocyte, proliferating and producing sex steroids and disparate growth factors.
70
Write brief notes on the following topics. | ZONA PELLUCIDA
a relatively thick extracellular coat that surrounds all mammalian oocytes, ovulated eggs, and preimplantation embryos
71
Write brief notes on the following topics. | CAPACITATION OF SPERM
sperm undergo a change in the motility pattern called hyperactivation the physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg
72
Write brief notes on the following topics. | ERRECTION OF STALLION PENIS
``` 2) Musculovascular Penis – Stallion, Human – Large corpus cavernosum fills with blood during erection – No sigmoid flexure – Retractor penis muscle ```
73
Write brief notes on the following topics. | GLYCOPROTEIN HORMONES
LH FSH hCG thyroid stimulating hormone
74
Write brief notes on the following topics. | ELECTROEJACULATION
Animals untrained or physically unable to mount – Reliable method of semen collection – Must be performed or under the supervision of a veterinarian – Sedation and restraint of male required – Localised electrical stimulation of the nerves controlling ejaculation – Probe is inserted into rectum and series of electrical pulses released – increasing in voltage from 5-16 volts – Duration of 1-2 sec each – Rest period of 0.5-2 secs between pulses – Continues until ejaculation
75
Write brief notes on the following topics. | K STRATEGISTS
* Large body size * Long lifespan * Long gestation * Single offspring * Slow rate of development * Long birth interval * Stable popn size Elephants, humans, and bison
76
Write brief notes on the following topics. | HERMAPHRODITES
a person or animal having both male and female sex organs or other sexual characteristics, either abnormally or (in the case of some organisms) as the natural condition. * Presence of both male and female gonads * Common in fish and invertebrates (true hermaphrodites) * Atypical in most vertebrates (intersex) * May still be fertile (but only towards one sex)
77
Write brief notes on the following topics. | INHIBIN
Inhibin is a protein secreted by the Sertoli cells in men and by the granulosa cells in women. It inhibits the synthesis and release of the follicle-stimulating hormone in the pituitary gland and reduces the hypothalamic LH - releasing hormone content

ANSC3102 (18 decks)

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