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Veterinary Physiology > Pregnancy and Parturition > Flashcards

Pregnancy and Parturition Flashcards

1
Q

Implantation

A

First stage in development of the placenta
Occurs when the embryo become fixed in position and forms a physical and functional contact with the uterus
2-5 weeks after fertilisation
Blastocyst undergo implantation or elongates rapidly to fill the uterine lumen

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2
Q

Stages of implantation

A
  1. Attachment
    - Close interaction of embyonic trophoblast and endometrial epithelial cells that is known as adhesion or attachment
    - Involves a tight intertwining of microvilli on the maternal and embryonic cells.
  2. Following that, blastocyst is no longer easily flushed from the lumen of the uterus.
  3. Gives rise to fetus portion of the placenta and becomes outermost layer of the placenta.
  4. Attach to the uterus, absorbs nutrients from uterus, allows maternal/fetal gas exchane produces hormones.
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3
Q

Superficial fuses to endometrium

A

Chrion fuses to endometrium.
The blastocyst remains in the uterine cavity (pigs, horses, carnivore)

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4
Q

Interstitial

A

Embyo invades endometrium and develops in endometrium
Rodents, primates

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5
Q

Placentation

A

The development of extra-embryonic membrane

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6
Q

Fetal placenta

A

Collective name of the membrane which consist of the chorion, allantois and amnion

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7
Q

Chorion

A

Outermost-associate with endometrium

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8
Q

Amnion

A

Envelops the fetus and contains amniotic fluid in the amniotic cavity

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9
Q

Allantoic cavity/Urachus

A

Space between the two layers of allantois

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10
Q

Allantois outer layer

A

Fused to chorion

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11
Q

Inner layer of allantois

A

Fused to the amnion

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12
Q

Functions of the fetal placenta

A

yolk sac - early supply
amnion - fetal protection
Allantois - fetal blood supply and waste
Chorion- maternal link

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13
Q

Yolk sac

A

Early nutrient supply for early embryo
Picks up uterine secretions from endometrium to stimulate early embryonic development
Site of primodial germ cells
It regresses as the allantois development
Contains blood vessel
Connected to the fetal intestine

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14
Q

AMNION

A

Develops form trophoblast and mesoderm
Non- vascular
Fluid filled - produced by fetus, reservoir for urine and waste
Protective cushion, protects fetus from injury and external shock
Ruptures at birth
Provides lubrication for parturition
Prevents lungs from collapsing and opens digestive tract

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15
Q

Allantois

A

Originates from mesoderm and rises from hindgut
Fuses with chorion
Carries blood vessels of placenta
Umbilical cord attaches fetus to allantois
The blood vessels acts as a carrier of nutrients and waste products between fetus and mother

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16
Q

Chorion

A

Developed from trophoblast and endoderm
Give rise to fetus portion of the placenta and becomes outermost layer of the placenta
-Attaches to uterus, absorb nutrients from uterus, allows maternal/fetal gas exchanges, produces hormones
Dont contain blood vessels

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17
Q

Diffuse placenta

A

Horse, pig
When attachment (extension of chorionic villi) of fetal membranes to the endometrium is continuous throughout the entire surface of the fetal membrane

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18
Q

Cotyledonary placenta

A

Ruminants
Mushroom-like from the endometrium
Multiple, discrete area of attacment called cotyledons formed by interactions of patches of allantochorion with endometrium
The fetal cotyledons are attached to the maternal caruncles, a combination known as placentome

19
Q

Zonary placenta

A

Placenta takes the form of a complete or incomplete band of tissues surrounding the fetus
Attached by girdle-like band tha encircles the placenta
Carnivores like dogs and cats, seals, bears and elephants

20
Q

Discoidal placenta

A

Attached as disk-shaped area
Singlle placenta
Discoid in shape
Primates and rodents

21
Q

Gestation

A

Period of time during which fetus develops, dividing via mitosis inside the female
The fetus receives all nutrion and oxygenated blood from the female, filtered through thep placenta, which is attached to the fetus’s abdomen via an umbilical cord

22
Q

Why last 3rd of pregnancy fast

A

greater maintenance of dam, growth of fetus and for lactation
> greater requirement for nutrients

23
Q

Relaxin hormone

A

Causes connective tissue to stretch uterine muscle
Causes pelvic canal to expand during gestation

24
Q

Estrogen

A

From placenta.
Synergistic action with prostaglandin for mammary development

25
Placental lactogen
Mammary development and fetal growth
26
Fetal Nutrition
Blood gas exchange at chorion- endometrium attachment Placenta highly permeable to water and electrolytes stored in and exchange between allantoic and amniotid fluids Placenta converts glucose to fructose Allow storage in allantoic fluid Fetal fat formed from fatty acids transferred across the placenta - omega 3 & 6 fatty acid - DHA Fetus makes protein from transferreda amino acids Water soluble vitamins cross placenta easier than fat soluble vitamins Minerals are transferred across placenta Antibodies dont cross placenta - newborn will get these antibodies from colostrum
27
Factors affecting pregnancy DAM
shorted if young dams
28
Factors affecting pregnancy FETUS
no of fetus males are born earlier larges-sized is born earlier Hormones
29
Factors affecting pregnancy GENETIC
Breed of progeny EG: angus vs hereford, bos taurus vs bos indicus
30
Factors affecting pregnancy ENVIRONMENT
High temperature can reduce gestation length More stress, earlier born Nutrition
31
Pregnancy diagnosis
1. Hormonal diagnosis - plasma progesterone levels between 18-25 days after mating or insemination (low=not, high=yes). 2. Rectal palpation - left hand into rectum and feel cervix (in centre of pelvic cavity=no, in abdominal cavity=yes) Accuracy after 5-6 weeks 3. Abdominal ballottement 4. Ultrasound technique- accuracy from day 60 5. X-ray 6. Laparotomy 7. Laparoscopy
32
Parturition/labor
Physiological process by which pregnant uterus delivers fetus and placenta from maternal organism
33
Hormone changes during parturition
Progesterone- reduce rapidly 1-2 days before parturition Prolactin - Increase rapidly 1-2 days b4 parturition Relaxin - increase to max 1 day before parturition, relax pelvic area Estogen and FSH - increase to stimulate birth, assist in the production of uterine muslce contractile proteins b4 parturition Estrogen - signal secretion of PGF2 alpha that occur in the immediate prepartum period Fetal cortisol - increase rapidly, more compared to maternal cortisol, determines when is parturition
34
Prior to parturition
+ adrenal cortisol > +estrogen concentration > increased synthesis in uterus of oxytocin receptors > stimulate +production of PGF2a and PGE2 > cause uterine contraction during labour
35
Signs of parturitiom
Frequently adopt posture of urination Myometrium contracts Rhythmic contraction of uterus Fetal positioning Restless Nesting behaviour Enlargement of mammary gland, teats Chorion-allantois ruptures Dam recumbent
36
Dilation of cervix
1. 2-6 hours, cow heifers 12 hours 2. Uterine contractions become coordinated and regular due to decline in progesterone, estrogen & PGF2a induced 3. Fetus pushed against cervix-amnion, stimulate oxytocin release, chriallantoic membrane may break, dilates cervix 4. Pressure of fetus on cervix stimulates oxytocin release and reflex contraction of abdominal muscle
37
Expulsion of fetus cow - 5-2 hours
1. Strong uterine contraction due to synergistic actions of high estrogen, PGF2a and oxytocin 2. Strong abdominal muscle contractions 3. Amino ruptures, lubricates vagina & vestibules 4. Contraction force the calf legs and head to spread in cervix 5. Fetus passes through vagina-vestibule
38
Expulsion of the placenta (4-5 hours, cow)
1. Uterine contraction continue 2. Blood forced from cotyledon villi-shrinkage separates cotyledon and caruncle 3. Contraction push placenta out
39
Fetus discharged
- Dam gets up and licks fetus nudges new born - Separation of villi from uterus - Fetal membranes discharged - New born goes for milk
40
Causes of retained placenta
Infection Calving stress Weak uterine contraction
41
Dystocia
Abnormal or difficulty childbirth or labour - prolonged spontaneous calving or prolonged or severe assisted extraction - due to incoordinate uterine activity, abnormal fetal lie or presentation, absolute or relative cephalopelvic disproportion
42
Causes of dystocia
Feto-pelvic disproportion Fetal malposition Uterine inertia Vulval or cervical stenosis Uterine torsion
43
Involution
process the uterus returns to its non-pregnant size after parturition cow - 21 to 35 days ewe and sow - 24 to 28 days bitch - 12 weeks

Veterinary Physiology (9 decks)

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