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Physiology > Placentation, Gestation, Parturition > Flashcards

Placentation, Gestation, Parturition Flashcards

1
Q

Placenta

A

Organ of physiologic exchange

  • fusion of fetal membranes to endometrium
  • size/functions change with pregnancy stages
  • expelled after parturition (stage 3)
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2
Q

Placenta is classified based on

A

Gross shape and distribution of villi

- microscopic structure of feto-maternal barrier

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3
Q

Villi function

A

Bring fetal vessels into close proximity to maternal blood vessels

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4
Q

Diffuse

A

Attached everywhere

- mare and sow

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5
Q

Cotyledonary

A

Attachment occurs in small, multiple focal areas

- ewe, doe, cow

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6
Q

Zonary

A

Attachment occurs in a specific circular zone around the fetus
- bitch and queen

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7
Q

Discoid

A

Attachment occurs in one large single area (large cotyledon)

- primates and rodents

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8
Q

Convex villi

A

Cow, giraffe

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9
Q

Concave villi

A

Sheep, goat

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10
Q

Fetal _____ fuse with maternal ______ to form ______

A

Cotyledons; caruncles; placentomes

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11
Q

Maternal caruncles

A

Specialized projections of uterine mucosa

- convex in cow, concave in ewe/doe

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12
Q

Functional unit

A

Placentome

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13
Q

Utero verdin

A

Dark green fluid

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14
Q

Binucleate giant cells

A

Move from fetal side across junction, into maternal side to secrete substances (pregnancy specific protein B) that are used to detect pregnancy
- basis for pregnancy blood test

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15
Q

Epitheliochorial

A

Least intimate, both maternal and fetal epithelium are intact

  • greatest barrier
  • pig, horse, cow, ewe, doe
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16
Q

Endotheliochorial

A

Complete erosion of endometrial epithelium

- dog, cat

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17
Q

Hemochorial

A

Chorionic epithelium is in direct apposition to maternal pools of blood

  • intimate, close attachment
  • primates, rodents
18
Q

Degree of invasiveness is important for transfer of _____

A

Maternal antibodies

- need to colostrum is high in pigs, cows, ewes

19
Q

Deciduate

A

Portion of endothelium is shed with placenta

- dog, cat, rodents, primate

20
Q

Adeciduate

A

Endometrium is left intact at time of placenta expulsion

- pig, cow, horse, sheep, goat

21
Q

Placental functions

A
  • metabolic exchange

- substitutes for fetal GIT, lung, kidney, liver, endocrine glands

22
Q

The placenta produces hormones that _____

A
  • stimulate ovarian functions
  • maintain pregnancy
  • stimulate mammary function
  • assist in delivery of fetus
23
Q

In which species does the placenta NOT have a role in pregnancy maintenance?

A
  • bitch
  • queen
  • camels
  • sow
  • doe
24
Q

The placenta takes over from primary (ovarian) source of progesterone in _______

A

Cow, ewe, and mare

  • cow: 6-8 mos
  • ewe: 50 days
  • mare: 70 days
25
Q

Endometrial cups are unique to the _____

A

Mare

  • produce equine chorionic gonadotropin
  • temporary structure
  • embed and invade maternal endometrium
  • could measure eCG level to determine pregnancy (is highest around 80 days)
26
Q

Placental circulation

A

2 circulations parallel to each other

  • blood does not intermingle between dam and fetus
  • close enough for gas and nutrient exchange to occur
27
Q

Freemartinism

A

Blood can be co-mingled between twins of cattle but rarely of other species

  • anastomosis of fetal circulation
  • mascinulizes female = sterility
28
Q

What species has the most variable gestation length?

A

Mare

- 340-360 days

29
Q

Placental takeover of P4 production in the cow and mare

A

150 days

30
Q

Gestation lengths

A
  • cow: 283 days
  • ewe: 152 days
  • doe: approx 230 days
  • sow: 114 days
  • dog: 58-68 days
  • cat: 64-67 days
  • camelids: 11 months
31
Q

Amniotic fluid

A
  • origin: fetal urine, secretions from respiratory and buccal cavity, maternal circulation
  • functions: protects fetus from external shock, prevents fetal skin adhesion to membrane, dilates cervix and lubricates birth passage
32
Q

Allantoic fluid

A
  • origin: fetal urine, secretions of allantoic membrane
  • functions: brings allochorion into close apposition with endometrium, stores fetal excretory products not transferred to mother, maintains osmotic pressure of fetal plasma
33
Q

Fetal fluids

A

Function to protect and bathe the fetus

  • lubricate birth canal
  • elimination of waste
  • maintains osmotic pressure of fetal plasma, prevents fluid loss to maternal circulation
34
Q

Hippomanes

A

Allantoic calculi, similar to bladder stones

  • do not serve physiologic purpose
  • seen occasionally in cattle, common in equines
35
Q

Stage 1 of parturition

A

Initiation of myometrial contractions

  • P4 block has been removed via PGF
  • P4 converted to E2
36
Q

Stage 2

A

Expulsion of fetus

- strong myometrial and abdominal contractions expels fetus

37
Q

Stage 3

A

Expulsion of fetal membranes

38
Q

Active straining is due to

A

Abdominal contractions

39
Q

Fetal stress drives the ____

A

Parturition cascade

40
Q

Myometrial contractions

A

Uterus is transformed from P4 dominated “relaxed” state to an “active” state

  • PGF synthesis and release is increased
  • act jointly to initiate uterine contractions needed to dilate the cervix and deliver the fetus
41
Q

Immune stats

A

Fetus synthesizes little to no antibodies

  • acquires antibodies from dam while in utero (rat, human)
  • secretes antibodies in colostrum (farm animals)
  • related to impermeability of epitheliochorial placenta to antibodies

Physiology (33 decks)

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