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APBI 411 Reproductive physiology and technology > Establishment of Pregnancy > Flashcards

Establishment of Pregnancy Flashcards

1
Q

When does the embryo enter the uterus?

A

after fertilization

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2
Q

How long does it take an embryo to enter the uterus in:
Swine
Cattle
Mares

A

Swine: 48-56 hrs
Cattle: 72 - 96 hrs
Mare: 144 hrs

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3
Q

At 5-6 days of development, where is the embryo and what is it called?

A

uterus, morula

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4
Q

how long until the blastocyst fully forms?

A

7-9 days

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5
Q

How long is the gestation period of swine?

A

115 days

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6
Q

How long is estrus? (swine)

A

48-72 hrs

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7
Q

What does the loss of corpus luteum function lead to? (swine)

A

abortion within 36 hrs

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8
Q

When does a blastocyst form in swine?

A

day 5

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9
Q

When does hatching occur in swine?

A

day 6-7

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10
Q

When does the ovoid form arise in swine?

A

day 10

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11
Q

When does the filamentous form arise in swine?

A

day 16

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12
Q

What happens on day 16

A
  • Estrogen production causing uterine secretions of protein, PGF2alpha, PGE2 and plasminogen activator
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13
Q

What does the blastocysts escape from the zona provide?

A

the first cell to cell contact between the conceptus and maternal uterine epithelium

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14
Q

Why must the conceptus physically cover a large portion of the maternal endometrium?

A

to regulate the release of prostaglandin F2alpha to prevent luteolysis

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15
Q

When does the conceptus undergo a rapid process of trophoblast elongation?

A

day 12

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16
Q

What is migration and equal spacing modulated by?

A

peristalic contractions of the myometrium stimulated by the developing conceptus
- conceptus production of histamine, estrogen and prostaglandins all play role in stimulating local myometrial activity to move conceptus

17
Q

What is unique about the equine conceptus following hatching from its zona pellucida?

A

it is surrounded by an acellular capsule that forms between the trophoblast and zona when the embryo enters the uterus on day 5.

18
Q

What does the acellular capsule surrounding the equine conceptus do?

A
  • may play a role in migration and protection of the conceptus
19
Q

Why does the equine vesicle migrate so much between the uterine horns?

A
  • essential for inhibition of luteolysis
20
Q

What does the conceptus production of prostaglandin involved in?

A

stimulating myometrial contractility to propel the vesicle through the uterine horns

21
Q

What is induced by conceptus production of estrus? What does it cause?

A

increase in uterine diameter, uterine tone, and thickening of the uterine wall - causes fixation of vesicle within the uterine lumen on day 16 of gestation

  • uterine secretions
  • maintenance of CL during early pregnancy
22
Q

What is the proper orientation of the embryo? How is this achieved?

A

embryo orientated to the ventral region of the vesicle.

  • results from regional differences in the chorion thickness as mesodermal layer migrates down between the trophectoderm and endoderm.
  • myometrial contractions
23
Q

What is the embryoblast?

A

inner cell mass of embryo

24
Q

How does the embryoblast become exposed to the maternal environment?

A

degeneration of the trophectoderm covering it

25
Q

When does the conceptus undergo logarithmic growth and an elongation phase?

A

day 11 postestrus in ewes + sows, day 14-15 in cows

26
Q

What has happened by day 18 of gestation? How does it occur?

A

the conceptus has extended into the contralateral (opposite to CL) horn
- occurs through continual hyperplasia of trophoblast

27
Q

What does expansion of the trophoblast permit?

A

the conceptus to extend its placental membranes throughout the uterus and block the epsilateral horn synthesis of PGF2alpha to prevent luteolysis

28
Q

What does conceptus elongation occur by in sows?

A

cellular reorganization and remodeling

29
Q

How does the shape of a mares conceptus change as it grows?

A
  • does not undergo a transformation from spherical to filamentous, will increase in diameter until it becomes fixed in the uterine horn
  • shape of the placenta will conform to the shape of the uterus
30
Q

What is luteolysis? Why does it occur?

A

It is the signaling of the conceptus to the maternal system in order to block the regression of the corpus luteum in order to maintain luteal progesterone production.

31
Q

How does the conceptus signal its presence to the maternal system?

A

it synthesizes and secretes steroids and/or proteins which serve to modulate the synthesis and/or release of luteolytic prostaglandin F2alpha from uterus + prevent CL regression

32
Q

What is maternal recognition of pregnancy?

A

the critical period in which the conceptus must signal its presence to the maternal system in order to block luteolysis and allow pregnancy to be established

33
Q

What is the signal for maternal recognition in pigs? Where is it produced?

A

production of estrogens by conceptus

- Estrone sulphate

34
Q

how is maternal recognition of pregnancy established in mares?

A

secretory proteins including isoelectric variants provide the signal by inhibiting endometrial PGF2alpha production.
–> eCG equine chorionic gonodotropin

35
Q

In primates, what is the main role of progesterone during pregnancy development?

A
  • maintinence of uterine glands

- increase in blood supply

36
Q

What does the hypertrophy of the myometrium in primates during pregnancy development do?

A
  • glandular development
  • Edema
  • Hyperemia
37
Q

What is involved in implantation of conceptus?

A
  • intimate contact
  • nutrient exchange
  • endocrine function
  • apposition
  • cellular invasion and interaction
  • maternal recognition of pregnancy
  • initiation of placentation
38
Q

What is maternal recognition of pregnancy required for?

A
  • maintenance of CL
  • continued endometrial development
  • secretory activity
39
Q

What is the signal for maternal recognition in sheep/cows?

A

interferon-tau (IFN-t)

APBI 411 Reproductive physiology and technology (10 decks)

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