Implantation Flashcards

1
Q

What does compaction in morula lead to in the development of the blastocyst

A

POlarity and asymmetric division that results in daughter cells having different properties from each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the trophectoderm form in a blastocyst and what is it

A

Forms placenta

It is a layer of trophoblast cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the inner cell mass in a blastocyst form

A

Embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the zona pellucida do

A

Prevents blastomeres falling apart during early cleavage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 phases of implantation

A

Attachment
Adherence
Invasion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When does attachment of blastocyst to endometrium occur

A

Only in the Luteal phase of the endometrium when it can provide nutrition (Uterine milk)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Once attached/implanted, how does the blastocyst obtain nutrients and what is this process called

A

Diffusion

Histiotrophic Nutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is progesterone and oestrogen like in luteal phase

A

High

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do the high progesterone and oestrogen cause the epithelial cells lining the endometrium to do and what is this called

A

Lose surface glycocalyx

Lose anionic charges

Flatten their microvilli

Have thin mucin coat

This is called Primary Decidualisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the implantation window

A

It is 2-3 day period during mid luteal phase where hatched blastocyst can adhere during this window

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does the blastocyst communicate to mother that it is still there so she doesn’t; get rid of it

A

Long range communication which alters the pituitary ovarian axis

1) Trophoblast cells secrete hCG which is an analogue of LH
2) hCG carried to ovary and binds to LH receptors on granulose cells of corpus lute which continues to produce progesterone and suppresses luteolysis
3) This prolongs life of corpus lute
4) Corpus luteum continues to produce progesterone up to 4 months. Thereafter, placental production is high enough to take over
5) Endometrium remains in progesterone dominated secretory phase throughout gestation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does adhesion between trophoblast and epithelial cells of endometrium lead to and what is this called

Why does this occur

A

changes in stroma in the endometrium. This spreads to areas surrounding the blastocyst and along the uterus

This is called Secondary Decidualisation

-Happens because of high progesterone and hCG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the ‘Secondary Decidualisation’ spread to create

A

3 Decidual layers

Decidua basalis (endometrium underlying the conceptus. This shows the highest changes as this is where the conceptus needs to burrow into. This is called the basal plate of the placenta)

Decidua capsularis (superficial portion overlying the conceptus)

Decidua parietali (remaining uterine mucosa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does the endometrium enhance attachment to the blastocyst

A

Produces LIP which acts as a ‘come hither’ messenger

Downregulates anti-adhesive cell surface mucin MUC1 which normally acts as a ‘go away’ molecular message

Epithelial cells adjacent to the blastocyst produce heparin binding EGF-like growth factors and HSPG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What may high levels of MUC1 be behind

A

Misscarriages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do trophoblast cells enhance the attachment between the blastocyst and endometrium.

A

Upregulate HSPG. HSPG from both cell types bind together (ZIPPER theory) :

Integrin binding occurs between the 2 cell types

Endometrial EGF binds to trophoblast EGF receptors

17
Q

How is the Chorion Plate and Syncytiotrophoblast formed

A

After attachment, the single layer of trophoblast in the trophectoderm proliferates to form numerous cut-trophoblast cells and creates the chorionic plate of the placenta

The cut-trophoblast cells fuse with each other to become a single multinucleate tissue layer without cell boundaries called the syncytiotrophoblast

18
Q

What is syncytiotrophoblast maintained by and why

A

Continual fusion of underlying proliferating cut-trophoblast cells throughout gestation. This is because it lacks proliferative capacity

19
Q

Where does the embryo grow

A

wall of the uterus