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RPL > Gestation > Flashcards

Gestation Flashcards

1
Q

Definition of Gestation

A

Period of pregnancy

Fertilization –> Parturition

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2
Q

Definition of Syngamy

A

Merging of sperm and oocyte nuclei

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3
Q

Name the stages of an embryo

A

Zygote (1 cell)
Morula (8-16 cells)
Blastocyst ( >32 cells)

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4
Q

…… is a fluid-filled cavity surrounded by trophoblasts

A

Blastocoele

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5
Q

How is the blastocoele formed

A

Outer cells connected by tight junctions pump Na into the intracellular space causing osmosis causing an accumulation of water in between the outer and inner cells forming the ICM and blastocoele

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6
Q

Define Differentiation

A

True embryo period, during which cells form specific organs in the body of the embryo (Rapid change in size)

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7
Q

Define inner cell mass (ICM)

A

group of cells congregated at the polar end of the blastocyst (body of the embryo)

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8
Q

When does a blastocyst “hatch”

A

Zona pellucida thins because of the growing blastocyst inside, when the Zona pellucida cracks the blastocyst escapes and is then known as a hatched blastocyst

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9
Q

What originates from the endoderm

A

Digestive system
liver
most internal organs

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10
Q

What originates from the Mesoderm

A

Skeletal system
muscles
circulatory system
reproductive system

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11
Q

What originates from the Ectoderm

A 
nervous system
sense organs
hair
skin
mammary glands
hooves
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12
Q

endodermal+ mesodermal layers=?

A

yolksac and allantois

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13
Q

mesodermal + ectodermal layers =?

A

amnion and chorion

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14
Q

Functions of the amnion

A

Contains fluid to suspend the embryo

Provides turgidity to protect the embryo

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15
Q

At how many days can heartbeat be detected in cows vs sows

A 
cows= Day 22
Sows= Day 16
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16
Q

what are the prerequisites for placentation of an embryo

A

complete organ development

functional circulatory system

17
Q

name the three stages an embryo goes through after fertilization

A

Cleavage
differentiation
growth

18
Q

define cleavage

A

Cell division without growth

19
Q

What replaces the zona pellucida in mares after hatching

A

The embryonic capsule

20
Q

Function of the yolk sac

A

Provides early nutrients to the embryo before regressing and becoming part of the primitive gut.

21
Q

What determines the differentiation into female

A

Absence of the Y chromosome (SYR)

22
Q

Function of the SYR

A

Stimulation of medulla of embryonic gonad to differentiate to testes (Sertoli and Leydig cells)
Inhibition of ovarian development

23
Q

How do Sertoli and Leydig cells help with Wolffian duct development

A

Sertoli cells secrete Mullerian inhibiting factor

Leydig cells secrete testosterone to initiate Wolffian duct development

24
Q

Function of 5 alpha-reductase in the urogenital sinus

A

Converts testosterone to dihydrotestosterone

Dihydrotestosterone differentiates urogenital sinus and genital tubercule to external male genitalia

25
Q

What effect does low 5 alpha-reductase or testosterone have on males

A

Causes female appearing genitalia

26
Q

What enzyme found in brain cells that release GnRH is responsible for converting testosterone to estradiol

A

Aromatase

27
Q

When is an embryo called foetus

A

After completion of differentiation

28
Q

When does hair appear around the muzzle of the animal?

A

Day 150

29
Q

When does hair appear on the entire body?

A

Day 230

30
Q

Define maternal recognition

A

`Biochemical process by which the embryo signals its presence to the uterus not to release PGF2 alpha and regress the corpus lutheum.

31
Q

Luteolysis

A

regression of the Corpus Lutheum.

32
Q

What is the function of bovine/ovine interferon tau

A

Antiluteolytic function through:

  • prostaglandin biosynthesis
  • regulation of uterine oxytocin levels

And inhibition of PGF2a to below luteolytic concentrations

33
Q

Where is PGE2 produced in sheep

A

venous plasma

34
Q

What is the antiluteolytic signal in pigs?

A

Oestradiol from the embryo to the maternal unit.

35
Q

How can Psuedopregnancy be induced in pigs?

A

Oestrogen injection on D11-15

36
Q

When is the critical period for maternal recognition in a mare?

A

Day 14-16

37
Q

define Lutenization

A

The process whereby granulosal and thecal cells are transformed into luteal cells. Lutenization is brought about by the hormone LH

38
Q

lutectomy

A

removal of the Corpus Lutheum

RPL (13 decks)

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