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REPRO > Maternal recognition of pregnancy > Flashcards

Maternal recognition of pregnancy Flashcards

1
Q

What species have early conception factor and how does it work?

A

Found in Mice, sheep, cattle, pigs, women it gives a Maternal response within hours of fertilisation.
ECF acts to protect the early embryo by binding to T lymphocytes

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2
Q

What is the key hormone that initiates luteolysis?

A

The key Luteolytic hormone is prostaglandin F2Alpha which is uterine derived.
NB. Prostaglandin E2 promotes the CL!!

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3
Q

What receptors reappear in the endometrium as progesterone starts to fall?

A

endometrial oxytocin receptors (OXTR)

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4
Q

How do OXTR receptors help initiate luteolysis?

A

Oxytocin (from CL) binds to OXTR and stimulates PGF2 release in a pulsatile manner which is sent back to the ovary via the counter current system (this is because the half life of PGF2A is very short and metabolised quickly by the lungs)

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5
Q

What happens to uterine glands under the influence of progesterone?

A

Glands will grow down and coil under the influence of progesterone and secrete a mixture of growth factors, amino acids, minerals and ions that we call histotroph.

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6
Q

How does progesterone maintain pregnancy?

A

Progesterone Suppresses myometrial contractions and luteolytic mechanism and suppresses FSH/LH secretion which reduces follicular development and indirectly suppresses ovulation

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7
Q

What is the embryonic anti-luteolysis signal in the ruminant?

A 
interferon tau (IFNT) 
Blastocyst’s most abundant protein at this time
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8
Q

In the ruminant when is the embryonic signal produced? which cells produce it?

A

Expression initiated during trophoblast elongation (as its produced by the trophoblast cells)
Expressed in the trophectoderm
Only expressed day 12-24 of pregnancy

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9
Q

In ruminants what stimulates the embryo to produce the MR signal?

A

Stimulated by uterine growth factors (e.g. IGF1 and 2)

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10
Q

Will a bigger embryo produce more MR signal?

A

Production related to embryo size- as it gets bigger its less likely to be luteolysed

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11
Q

How does INFT maintain pregnancy?

A

IFNT acts on the endometrium and supresses the OXTR expression. This stimulates protein synthesis critical for the embryo and provides and antiviral activity.
Suppresses PGF2a pulsatile secretion and maintains progesterone (indirectly)

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12
Q

In pigs what is the luetolytic hormone?

A

The Luteolytic hormone is still PGF2A and oxytocin my be involved.

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13
Q

In pigs what is the embryonic signal for anti-luteolysis? How does it work?

A

The embryonic signal is oestrogen which is secreted before implantation (just detectable in plasma) and redirects flow of PGF2A away from the uterine vein. Transfers it from an endocrine secretion to an exocrine secretion of PGF2A.

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14
Q

Do pigs produce INFT?

A

In pigs there is a massive blastocyst elongation (metres) so some interferon produced but it’s not anti-Luteolytic.

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15
Q

In horses what causes luteolysis? How does the embryo stop this?

A

Oxytocin stimulates luteolytic PGF2a and the embryo supresses OXTR

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16
Q

In horses does the embryo produce interferon?

A

No

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17
Q

How does the horse embryo spred its embryonic signal if it doesn’t elongate for many days?

A

The conceptus migrates around the uterus stimulated by prostaglandins

18
Q

What else do equine embryos produce?

A

Blastocyst produces oestradiol but its role in MRP still unresolved

19
Q

What is the embryonic signal in primates?

A

Chorionic gonadotrophin “rescues” CL

hCG produced by syncytiotrophoblast cells and acts on LH receptor on CL which suppresses PGF2a

20
Q

How is MRP different in rodents?

A

Mating leads to Pseudopregnancy if not real pregnancy so prolactin is secreted and the luteal phase is extended to 10-14d
MRP is produced late and placental lactogen takes over once prolactin secretion has finished

21
Q

What is the embryonic signal in the bitch?

A

none

22
Q

Around what day of pregnancy is this signal released?

A

12-16 days

23
Q

What is the cause of pseudopregnancy? What hormone rises?

A

Occurs in monoestrus animals as a result of sterile mating or induced ovulation
Increased prolactin

24
Q

What is embryonic dipause?

A

Embryo does not immediately implant e.g. remains unattached and enters a “state of dormancy”

25
Q

What can cause embryonic dipause?

A

Can be facultative eg. In marsupials: due to sucking stimuli and metabolic stress of lactation of one joey the one in utero is delayed
Or can be obligate in deer and armadillo; wait for time birth for favourable conditions

26
Q

When is a placenta formed?

A

A placenta is formed when foetal membranes become closely attached to the uterine wall to facilitate physiological exchange of gases, nutrients and waste products.

27
Q

Name the foetal membranes and their function (4)

A

Amnion [Innermost fluid filled membrane (reptile, bird, mammal)]
Allows symmetrical growth & protection of foetus
Temperature control and foetal movement

Yolk sac
Surrounds yolk in reptile and bird eggs
In higher mammals it has a nutritional role in early pregnancy

Allantois
Sac from hindgut
Connection becomes umbilical cord

Chorion [Outer membrane]
Becomes foetal contribution to placenta
All placentas chorionic at some stage of development

28
Q

Name the three stages of embryo implantation

A

Apposition
Blastocyst or foetal membranes become closely apposed to uterine lining (epithelium)

Adhesion
a complex biochemical interaction between molecules on the trophoblast and epithelium

Firm attachment OR invasion of trophoblast into uterus
Depends on species
Non-invasive v invasive
In non-invasive mucin inhibits attachment

29
Q

Define Hemotrophic and Histotrophic

A

Hemotrophic – nutrition from circulating maternal blood

Histotrophic – nutrition from endometrium

30
Q

What is the difference between Deciduate v non-deciduate placentas?

A

Deciduate is shed after birth

31
Q

Name the layers between foetal blood and maternal blood in an epitheliochorial placenta

A 
*foetal blood*
Foetal endothelium 
Foetal connective tissue
Foetal epithelium 
Maternal epithelium 
Maternal connective tissue 
Maternal endothelium 
*maternal blood*
32
Q

What layer(s) are missing in an endotheliochorial placenta?

A

Maternal connective tissue and epithelium

33
Q

What layer(s) are missing in an haemochorial placenta?

A

No maternal layers, maternal blood just washes up against foetal epithelium (trophoblasts)

34
Q

What type of placenta does a sow have?

A

True epitheliochorial placentation
Diffuse
Non-deciduate

35
Q

What type of placenta does a cow have?

A

Synepitheliochorial placentation
Cotyledonary - Convex
Non-deciduate

36
Q

In cows what are binucleate giant cells (BNGC)?

A

Fetal chorion cells undergo replication without cytokinesis ad you end up with a binucleate giant cell (BNGC). These cells migrate until they reach the maternal layer where they fuse (or rather inject their contents) with a maternal cell and release their granules into the maternal circulation.

37
Q

What type of placenta does a mare have?

A

Epitheliochorial placentation
Diffuse
But, unique to equids, there is invasive activity of specialised trophoblast cells called “chorionic girdle cells” which give rise to the endometrial cups.
Non-deciduate

38
Q

What is present at day 30 in the pregnant mare?

A

At day 30 we have two types of placenta existing at the same time (the yolk sac and the allantois from the hindgut) and the junction between the two of these forms the chorionic girdle which initially implants into the equine uterus.

39
Q

What is the fat of the chorionic girdle cells?

A

So the cells from the chorionic girdle invade into the uterine wall, destroy the uterine epithelium then bunch up and form endometrial cups. These cups secret equine chorionic gonadotrophin. Leukocytes
then gather around the edge of the cups and eventually destroy them around day 110-120.

40
Q

What type of placenta does a bitch have?

A

Endotheliochorial
Zonary
Deciduate

41
Q

Describe placentation in the primate

A

Haemochorial placentation
Invasive
Decidual

Endometrial stromal cells proliferate and enlarge to become decidual cells
The decidua is the maternal placenta, decidual tissue is important in: Communication between mother and fetus and limits invasion of trophoblast

REPRO (30 decks)

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