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Therio > 1.4.1 Clinical Physiology of Pregnancy > Flashcards

1.4.1 Clinical Physiology of Pregnancy Flashcards

1
Q

summary of early development in the bovine: what does the embryo do once it enters uterus? what hormone does it produce? when does it fill the horn?

A

-embyo enters uterus from oviduct
>begins elongating
>produced INF tau - signal for maternal recognition of pregnancy in cows
>fills horn by day 24 (same side as CL)
>eventually fills entire unterus

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2
Q

what does the horse embryo have from day 7 - 22 that is unique among dometic farm animals?

A

capsule – The capsule is a glycoprotein layer surrounding the embryo and is critical for pregnancy to continue

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3
Q

what shape is the equine embryo (vs bovine?)

A

equine: sphere
bovine: elongated

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4
Q

what is the Phase of Early Mobility for the equine pregnancy? what is it essential for? how long does it last? what do we see wherever embryo is located? what happens if this process is disrupted?

A

– Essential for maternal recognition
– Embryonic signal is not known
– Mobility phase from entry into uterus until Fixation at 16 days
– Increased uterine contractions wherever embryo is located
– Embryo traverses entire uterus multiple times per day!!
– Anything that disrupts this results in pregnancy failure

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5
Q

when does the equine embryo settle in place? where? coincides with what for uterus and embryo?

A

-Embryo stops moving and settles in place at the base of one horn
* Fixation ‐ occurs at day 16
* Coincides with increase in uterine tone, rapid increase in diameter of embryo and changes in the capsule making the embryo sticky

-Fixation should occur at the base of a horn
– Need NOT be the side of ovulation

  • Then embryo orientation occurs with embryo proper at base of vesicle
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6
Q

after maternal recognition what maintains pregnancy in the various species? what is its source?

A
  • Progesterone is the pregnancy hormone – Reduces myometrial contractions
    – Exception is the equine (of course!)
  • The SOURCE of progesterone varies by species and stage of gestation
  • Some species keep the Corpus Luteum throughout pregnancy, some do not (need to know this! – this is important when determining how to terminate pregnancy)
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7
Q

bovine gestation length

A

280d

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8
Q

ovine gestation length

A

150d

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9
Q

goat gestation length

A

146d

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10
Q

sow gestation length

A

112d

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11
Q

bitch gestation length

A

63d

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12
Q

mare gestation length

A

341d

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13
Q

what does progesterone do?

A

Progesterone is the pregnancy hormone – Reduces myometrial contractions
– Exception is the equine (of course!)

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14
Q

Bovine:
Gestational Length and Source of Progesterone for Maintenance of Pregnancy

A

gestation: 280d

progesterone source:
CL - throughout
placenta - 150-250d

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15
Q

Ovine:
Gestational Length and Source of Progesterone for Maintenance of Pregnancy

A

gestation: 150d

progesterone source:
CL - <50-60d
placenta - >50-60d

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16
Q

Goat:
Gestational Length and Source of Progesterone for Maintenance of Pregnancy

A

gestation: 146d

progesterone source:
CL - throughout
placenta - 8-10% of P4

17
Q

Sow:
Gestational Length and Source of Progesterone for Maintenance of Pregnancy

A

gestation: 112d

progesterone source:
CL - throughout
placenta - no contribution

18
Q

Bitch:
Gestational Length and Source of Progesterone for Maintenance of Pregnancy

A

gestation: 63d

progesterone source:
CL - throughout
placenta - ?

19
Q

Mare:
Gestational Length and Source of Progesterone for Maintenance of Pregnancy

A

gestation: 341d

progesterone source:
CL - 120d *2nd degree CLs (cups)
placenta - >70d (estrogens, 5alpha pregnanes)

20
Q

progesterone vs estrogen in the bovine pregnancy over time

A

progesterone relatively high level and contant throughout, dips to 0 at end while estrogen low throughout, grows to peak at end

21
Q

how do progesterone and estrogen levels in the mare vs bovine differ during pregnancy?

A
  • High levels of estrogen in mare throughout
  • Low levels of progesterone after 150 days until close to term for mare
22
Q

significance of Endometrial cups in the mare
- when do they form, what are they made of, what do they produce?

A
  • Cups begin to form about day 35
  • Specialized fetal trophoblast cells that invade the maternal endometrium
  • Produce Equine Chorionic Gonadotropin
  • eCG is detectable from day 35 thru 120
23
Q

when is eCG detectable in the mare during pregnancy?

A

day 35 thru 120

24
Q

what does eCG do?

A

eCG has LH activity in horse
> Results in Secondary CL’s on ovaries
> which make Progesterone to maintain pregnancy thru day 120
– (remember eCG has FSH activity in ruminants for breeding management programs)

25
Q

description of the pregnancy hormone profile in the mare

A

-progesterone grows and peaks at about day 120
-eCG increases around day 35, peaks, and then decreases, stopping at day 120
-progesterone basically drops to 0 at day 150, only to increase again just before parturition
-estrogen increases at day a50, as do total progestagens which keep increasing until parturition

26
Q

when do the endometrial cups die off?

A
  • Have a pre‐programmed lifespan
  • Die off (or are destroyed?) about day 100‐120
27
Q

what happens if the fetus dies while endometrial cups are present?

A

– they remain, and continue to produce eCG
– This means the mare will not come back into heat until the cups regress

28
Q

how is pregnancy maintained in the mare if progesterone is low?

A

– the placenta is starting to “make stuff” (progestagens) by day 70 and by 120 days is the primary source of pregnancy hormones

29
Q

The rise in estrogens coincides with what during mare prgnancy?

A

a dramatic increase in the size of fetal gonads, due to eCG from the endometrial cups

30
Q

what is the case for fetal vs mare gonads between day 150-220?

A

fetal gonads are bigger than mares!

31
Q

fetal gonads during mare pregnancy pump out what? what do these chemicals do?

A

Fetal gonads pump out a steroid hormone precursor, DHEA (dihydroepiandrosterone) which is converted by the placenta to various estrogens (some are specific to the horse – eg. Equilin, and Equilenin)

– These are essential for normal fetal growth and development, normal myometrial contractions during labour and normal mammary gland development

– But – estrogens are not “required” for maintenance of the pregnancy

32
Q

what is responsible for the maintenance of pregnancy after the endometrial cups are gone at 120 days?

A

Fetal adrenal gland produces other progestagens of pregnancy in the mare (mostly 5 alpha pregnanes such as 5 α DHP and pregnenolone)
– These are biologically active in horses and appear to be responsible for the “progesterone block” of pregnancy
– Bind to equine progesterone receptor

Therio (13 decks)

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