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Exam block 3 > Exam 2: Lecture 25: Maternal Recognition Of Pregnancy And Placentation > Flashcards

Exam 2: Lecture 25: Maternal Recognition Of Pregnancy And Placentation Flashcards

1
Q

What has to happen before the embryo can attach to the uterus?

A

-Must develop within Zona Pellucida
-Susequently hatch from the ZP
-Undergo Maternal Recognition of Pregnancy (MRP)
-Form extraembryonic membranes

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2
Q

What are the steps of early embryogenesis?

A

-In ootid, male & female pronuclei along w/ 1st & 2nd polar bodies are present
-Fusion of male & female pronuclei into single diploid nucleus constitutes syngamy
-Shortly after, zygote undergoes cleavage (miotic divisions) & gives rise to daughter cells called blastomeres
-4 celled embryo give rise to 8-celled embryo
-After 8 celled stage, ball of cells is formed & this embryonic stage is referred to as a morula
-Cells of morula continue to divide & blastocyst develops consisting of inner cell mass (ICM), blastocoele, & trophoblast
-Finally, rapidly growing blastocyst hatches from zona pellucida & forms hatched blastocyst that is free-floating within the uterus

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3
Q

What are the cleavages/divisions of embryogenesis?

A

-Zygote (one cell following synamy)
-First division (cleavage) (two blastomeres, half size of zygote)
-Second division (cleavage) (four blastomeres, quarter size of zygote)
-Each blastomere is totipotent

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4
Q

What is totipotency?

A

-Ability of single blastomere to develop into fully formed individual animal

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5
Q

What are the 3 forces that govern the hatching of the blastocyst?

A
  1. Growth & fluid accumulation within blastocyst
  2. Production of enzymes by trophoblastic cells
  3. Contraction of blastocyst
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6
Q

What is this?

A

Zygote

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7
Q

What is this?

A

2-cell Embryo

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8
Q

What is this?

A

4-cell Embryo

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9
Q

What is this?

A

8-cell Embryo

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10
Q

What is this?

A

16-cell Embryo (Morula)

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11
Q

What is this?

A

Early Blastocyst

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12
Q

What is this?

A

Blastocyst

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13
Q

What is this?

A

Hatching Blastocyst

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14
Q

____ is a time of incredible conceptus growth

A

Post-hatching blastocyst growth

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15
Q

A ____ blastocyst remains spherical

A

Mare

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16
Q

A ____ blastocyst is filamentous, thread-like structure

A

Ruminant

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17
Q

____ accounts for the rapid expansion of the blastocyst & is essential to facilitate attachment to the uterus

A

Extraembryonic membrane development

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18
Q

What are the extraembryonic membranes of the preattachmnt embryo?

A

-Yolk sac
-Chorion
-Amnion
-Allantois

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19
Q

What gives rise to the chorion and amnion?

A

-Trophoblast, along with the primitive endoderm & mesoderm

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20
Q

____ develops from the primitive endoderm

A

The yok sac

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21
Q

The allantois will fuse with the chorion & the chorion will eventually attach to the uterus, while the amnion will

A

provide a fluid-filled protective sac for the developing fetus

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22
Q

While the embryo is developing in the uterus, what prevents luteolysis from occurring?

A

-Maternal recognition of pregnancy

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23
Q

What does maternal recognition of pregnancy do?

A

-Preserves the primary corpus luteum (CL)
-Maintains high levels of Progesterone
-In most cases, it is a conceptus mediated biochemical signal

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24
Q

____ must occur before luteolysis

A

Maternal Recognition of Pregnancy (MRP)

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25
What is the positive feedback system of luteolysis?
-Oxytocin receptors appear in endometrium in late luteal phase -Corpus luteum contains large amounts of oxytocin -Oxytocin release stimulates a pulse of PGF2a release -PGF2a stimulates more oxytocin
26
How does maternal recognition of pregnancy occur in ruminants?
-Interferon Tau (INF-T) produced by the trophoblastic cells inhibits oxytocin receptor synthesis thereby inhibiting PGF2a release
27
How does maternal recognition of pregnancy occur in the sow?
-Blastocyst produces Estrogen which re-routes PGF2a release into uterine lumen where it is destroyed -PGF2a secretion is changed from endocrine to exocrine
28
How does maternal recognition of pregnancy occur in the mare?
-Blastocyst migration through uterine lumen (entire uterus several times) causes reduced synthesis of PGF2a -Occurs between days 12-14 -PGE2? production by embryo
29
How does maternal recognition of pregnancy occur in the dog and cat?
-Probably doesn't require a signature from conceptus -The bitch's CL has similar lifespan when pregnant & non-pregnant -Queen's CL has similar lifespan when pregnant & induced to ovulate without conception
30
When the embryo proper is in the middle of the embryo, the mare is ____ days pregnant
30 days
31
How does the placenta develop?
-In all domestic animals, the chorioallantois is the origin of the placenta
32
What do the endometrial cups in the mare do?
-Produce pregnant mare serum gonadotropin (PMSG) --> now called equine chorionic gonadotropin (eCG) -eCG has FSH & LH like activity, so helps luteinize accessory & secondary corpora lutea
33
Will only have hCG in your system if
a placenta is present
34
Endometrial cups in the mare are in the _____ but made by _____
In the uterus, made by trophoblast cells
35
What is the function of the placenta?
-Temporary organ of metabolic interchange -Temporary endocrine organe (maintenance of pregnancy, induction of parturition)
36
The functional unit of the placenta involves the _____
Chorionic villi
37
What are the microscopic groups placental villi can be grouped into
Microcotyledons
38
What are the macroscopic groups the placental villi can be grouped into
Cotyledons
39
Placental classification is based on
Distribution of the chorionic villi -Diffuse -Cotyledonary -Microcotyledonary -Zonary -Discord Number of tissue layers between maternal & fetal blood -Epitheliochorial -Endotheliochorial -Hemochorial
40
What is a diffuse placenta?
-Almost entire surface of allantochorion involved in formation of placenta
41
What animals have a diffuse placenta?
-Horses -Pigs -Camelids
42
What is a cotyledonary placenta?
-Multiple discrete areas of attachments -Fetal portions called coytledons -Maternal contact sites are caruncles -Cotyledon-caruncle complex is called a placentae
43
What animals have a cotyledonary placenta?
-Ruminants
44
What is a zonary placenta?
-Area of attachment is complete or incomplete band of tissue surrounding the fetus
45
What animals have a zonary placenta?
-Carnivores like dogs & cats -Seals -Bears -Elephants
46
What is a discoid placenta?
-Area of attachment is discoid in shape
47
What animals have a discoid placenta?
-Primates -Rodents
48
This is a ____ placenta
Discoid
49
What animals have a convex cotylendonary placenta and what animals have a convex cotyledonary placenta?
-Convex = cow, giraffe -Concave = sheep, goat
50
What placenta is this?
-Cotylendonary (cow)
51
What type of caruncles?
Concave caruncles
52
Do cotyledons form early or late?
-Form very early
53
The caruncle is from the ____, the codyledon is from the _____, and the entire unit together is the _____
-Caruncle = dam (mom drives CAR) -Cotyledon = baby (baby sleeps in COT) -Entire unit together = placentome
54
What is clinically relevant regarding the placenta?
-The degree of invasiveness (number of tissue layers between fetal & maternal blood)
55
What is an epitheliochorial placenta?
-Last intimate, both maternal & fetal epithelium intact
56
What animals have an epitheliochorial placenta?
-Pig -Horse -Cow -Ewe -Doe
57
What is an endotheliochorial placenta?
-Complete erosion of endometrial epithelium
58
What animals have an endotheliochorial placenta?
-Dog -Cat
59
What is a hemochorial placenta?
-Chorionic epithelium is in direct apposition to maternal pools of blood
60
What animals have a hemochorial placenta?
-Primates -Rodents
61
What are all the tissue layers between fetus & dam?
-Fetal endothelial cells -Fetal connective tissue -Chorionic epithelial cells -Endometrial epithelial cells -Maternal connective tissue -Maternal endothelial cells
62
Which placental type needs colostrum because there are too many tissue layers to receive maternal antibodies?
-Epitheliochorial
63
What placental type can have colostrum but it isn't as important to receive it because there is some maternal antibody transfer?
-Endotheliochorial
64
What placental type does not need colostrum?
-Hemochorial
65
What is an example of an animal with this placenta? Diffuse, epitheliochorial
-Horses (microcotyledonary) -Pigs
66
What is an example of an animal with this placenta? Cotyledonary, epitheliochorial
-Ruminants (cattle, sheep, goats, deer)
67
What is an example of an animal with this placenta? Zonary, endotheliochorial
-Carnivores (dog, cat, ferret)
68
What is an example of an animal with this placenta? Discoid, hemochorial
-Humans -Apes -Monkeys -Rodents
69
What are the functions of the placenta?
-Metabolic exchange -Produce hormones that stimulate ovarian function, maintain pregnancy, stimulate mammary function, assist in parturition
70
How does the placenta produce hormones that stimulate ovarian function?
Equine chorionic gonadotropin (eCG, PMSG) in mare -Produced by endometrial cups of placenta (formed from trophoblastic cells) -Serves as stimulus to primary CL & stimulates accessory CL's
71
How does the placenta produce hormones that maintain pregnancy?
-Placenta secretes P4 in certain species
72
How does the placenta produce hormones that stimulate mammary function?
-Placenta secretes lactogen in ewes -> mammary
73
How does the placenta produce hormones that assist in parturition?
-Relaxin
74
What animals does the placenta not play a role in maintenance of pregnancy?
-Bitch -Queen -Camels -Sow -Goat (weird one)
75
Placenta takes over from primary (ovarian) source of Progesterone in
-Cow, ewe, & mare (at various times)

Exam block 3 (39 decks)

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