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Module 5 Week 3 > Anatomy Of Pregnancy: Components And Development Of The Mammalian Placenta > Flashcards

Anatomy Of Pregnancy: Components And Development Of The Mammalian Placenta Flashcards

1
Q

What is the placenta

A

Fluid-filled, extra-embryonic/ foetal membranes

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2
Q

Functions of placenta

A
  1. Protect developing embryo / fetus
  2. Provision of oxygen / nutrients from maternal circulation to foetus
  3. Removal of metabolic waste products from foetus
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3
Q

The placenta is composed of what 4 foetal membranes?

A

Yolk Sac
Amnion
Chorion
Allantois

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4
Q

What happens to the foetal membranes of placenta at birth?

A

Shed at birth

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5
Q

After fertilisation, blastocoele undergoes formation of… (the beginning of formation of placenta)

A
  1. Bilaminar embryonic disc
  2. Extra-embryonic membrane
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6
Q

What does the bilaminar embryonic disc consist of?

A

Hypoblast= endoderm
Epiblast= embryonic ectoderm

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7
Q

What does the extra-embryonic membrane consist of?

A

Hypoblast= endoderm
Trophoblast= extra-embryonic ectoderm/trophectoderm

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8
Q

What happens to size of blastocoele and why?

A

Massive ^ in size due to fluid accumulation inside of it

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9
Q

What are the functions of the blastocoele?

A

• Nutrition – diffusion across membranes
• Maternal recognition of pregnancy

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10
Q

Describe what happens to blastocoele once it ^ in size (the process of formation of placenta)
(-blastocyst wall becomes…
-blastocoele is now called…
-what happens to mesoderm after *hint questions)

A

-A third layer called mesoderm extends from embryo & enters space between endoderm and trophectoderm
-blastocyst wall becomes trilaminar (trilaminar omphalopleure)
-blastocoele is now called yolk sac
-after this the mesoderm splits into 3 layers:
1. Somatopleure
2. Splanchnopleure
3. Extraembryonic coelem/ exocoelum
-embryo begins to sink into somatopleure
-sac folds around embryo, meets dorsally and fuses to form the Amniotic Sac/Amnion
-the rest of the somatopleure is now called the chorion
-yolk sac temporarily fuses with chorion to give chorio-vitelline ‘placenta’
-then the Allantois is formed- formed directly from the embryo
-as Allantois develops it pushes out into extra embryonic coelom-into space between 2 mesoderm & continues to develop and eventually fills the extraembryonic coelom
-Yolk sac regresses and is engulfed
-allantois fuses with chorion forming chorio-Allantoic placenta- the final form of placenta which is what is gonna be in contact with the endometrium of the mother
-remnants of yolk sac contained within the umbilical cord
-umbilical cord connects the foetus to placenta and allows exchange of material to happen

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11
Q

What is the somatopleure layer of mesoderm a combination of?

A

Combo of external layers; trophectoderm + somatic mesoderm

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12
Q

What is the splanchnopleure layer of mesoderm a combination of?

A

Combo of internal layers; endoderm + splanchnic mesoderm
Wall of yolk sac

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13
Q

What is the exocoelum layer of mesoderm?

A

Resulting cavity between somatic + sphlanchnic mesoderm
Trilaminar

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14
Q

What happens after yolk sac fully formed?

A

The formation of the amniotic sac begins

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15
Q

What is the amniotic sac

A

-The next step of placenta formation
-surrounds embryo/foetus
-contains amniotic fluid and sometimes amniotic pustules (white spots & perfectly normal)

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16
Q

What is the function of the amniotic fluid?

A

Shock absorption

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17
Q

Describe the formation of the amniotic sac

A
18
Q

What does the temporary chorio-vitelline placenta allow for?

A

Easy diffusion

19
Q

What is the allantois?
Contains what?

A

Fluid filled structure formed directly from embryo/diverticulum of the hind gut
Contains fluids like urine, secretions & blood transudate

20
Q

What connects the foetus to the placenta at the end of placenta formation?

A

Umbilical cord

21
Q

What are chorionic villi
-function

A

Short projections found on surface of chorion
^ surface area for transfer of material

22
Q

Location of villi on placenta depends on…

A

Species

23
Q

What are the 4 types of placenta relative to location/spread of villi

A

Diffuse placenta—> overall whole of chorion
Cotyledonary placenta—> arranged in focal areas/patches
Zonary placenta—> in a band through centre of placenta
Discoid placenta—> disc shaped

24
Q

Which species has which type of villi placenta
-diffuse
-cotyledonary
-zonary
-discoid

A
  1. Mare, sow
  2. Ruminant
  3. Carnivore
  4. Human, monkey
25
Q

Histological classification-
What are the 6 layers which material has to pass through for nutrient exchange
(Another name for it is the epithelio-chorial placenta)

A

(3 maternal, 3 foetal)
1. Maternal endometrial endothelium
2. Maternal connective tissue
3. Maternal endometrial epithelium
4. Fetal chorion
5. Fetal connective tissue / mesoderm
6. Fetal endothelium
(3&4 in direct contact due to vill)

26
Q

Which animals have the epithelio-chorial placenta?

A

Pig, mare & ruminant

27
Q

What is the non-deciduate placenta vs deciduate placenta?

A

Non- • Fetal chorion and endometrial epithelium separate after birth
• Placenta expelled with no loss of maternal tissue

Deciduate- there is a loss of maternal tissue

28
Q

What is the endothelio-chorial placenta?

A

Instead of the maternal epithelium being in contact with fetal chorion, The fetal chorion invades maternal tissue & is now in contact with the maternal endothelium

29
Q

What is an advantage/disadvantage of the endothelio-chorial placenta?

A

+ve; Allows transfer of large molecules
-ve; more invasive; after birth when its shed it takes a little bit of maternal tissue with it

30
Q

Which species have the endothelio-chorial placenta?

A

Carnivores

31
Q

What are the 4 cellular layers of the endothelio-chorial placenta?

A

(1 maternal, 3 foetal) 1. Maternal endothelium
4. Fetal chorion
5. Fetal connective tissue / mesoderm
6. Fetal endothelium

32
Q

What is the haemochorial placenta?
-which species have this type
-deciduate or not?
-advantage?

A

• Fetal tissue invades maternal tissue & erodes/destroys endothelium
• Fetal chorion directly in contact with maternal circulating blood
• Eg. Humans & monkey
-very deciduate as very invasive
• Transfer of large molecules

33
Q

What are the 3 cellular layers of the haemochorial placenta?

A

(0 maternal, 3 foetal)
4. Fetal chorion
5. Fetal connective tissue / mesoderm
6. Fetal endothelium

34
Q

Umbilical cord

A

Cord of communication between foetus and placenta

35
Q

Name the 4 components found in umbilical cord and the function of each

A

1/ Umbilical veins:
• Carry oxygen & oxygenated blood & nutrients from chorioallantois to fetus
• in Ruminants – paired (2 of em)
• in Horse, carnivore, human - fused single vein
2/ Umbilical arteries:
• Carry foetal waste products from fetus to chorioallantois
• Paired
3/ Allantoic duct:
-formed from developing bladder, maintains fluid within cavity
• Drains urine from fetus into allantoic cavity
4/ Yolk-sac:
• Remnant present – thought to have some haematopoietic function in some species but mostly non functional

36
Q

Implantation vs attachment- page 14 of 15 go over this again

A
37
Q

What is marginal haematomas?

A

Areas where blood has collected due to destruction of blood vessels. Marginal means it has specifically developed along the periphery of a specific tissue.

38
Q

Whereabouts does marginal haematomas occur in a bitches uterus?

A

Along periphery of the zonary band

39
Q

What are some reasons/applications of US in the bitch

A

• Pregnancy detection
• Counting foetuses!
• Foetalviability
• Gestational age/ date of whelping

40
Q

At what day is foetal anatomy in a bitch identifiable on an US

A

Day 35

41
Q

Around what time can radiogrpahies be used for pregnancy detection in bitches

A

After day 42

42
Q

What is a radiography used for in pregnancy detections in a bitch?

A

Foetal numbers-count skulls
Difficult to assess viability/gestational age

Module 5 Week 3 (7 decks)

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