Implantation & placental function Flashcards
(33 cards)
where does fertilisation usually take place?
uterine tubues / fallopian tubes
vagina
uterus
cervix
endometrium
where does fertilisation usually take place?
uterine tubues / fallopian tubes
vagina
uterus
cervix
endometrium
how long after fertilisation occurs in the fallopian tubes doe the blastocyst enter the uterus?
3 days
4 days
5 days
6 days
7 days
how long after fertilisation occurs in the fallopian tubes doe the blastocyst enter the uterus?
3 days
4 days
5 days
6 days
7 days
how long after fertilisation occurs in the fallopian tubes doe the blastocyst hatch?
3 days
4 days
5 days
6 days
7 days
how long after fertilisation occurs in the fallopian tubes doe the blastocyst hatch?
3 days
4 days
5 days
6 days
7 days
how long after fertilisation occurs does the blastocyst implant into the uterine endometrium? [1]
day 8-9
how does the embryo communicate with the mother when reaching the uterus? [2]
- *1. It establishes physical and nutritional contact**
- Required for a supply of nutrients leading to growth – placentation
- *2. It signals its presence to the mother**
- Required to prevent luteal regression ((i.e. the corpus luteum generating and therefore collapse of the endometrium) – maternal recognition of pregnancy occurs due to hormone hCG
which hormone causes maternal recognition of the pregnancy?
LH
FSH
oestrogen
testosterone
hCG
which hormone causes maternal recognition of the pregnancy?
LH
FSH
oestrogen
testosterone
hCG
• Approx 6 days after fertilisation the blastocyst has differentiated into:
The outer cell layer called WHAT? [1]
The inner cell mass called WHAT? [1]
what do each of the above turn into? [2]
• Approx 6 days after fertilisation the blastocyst has differentiated into:
The outer cell layer called trophectoderm –> placenta
The inner cell mass called embryoblast –> embryo / fetus
describe what the stage apposition is of implantation and placental development
Apposition
positioning of the blastocyst within the uterine cavity, with the inner cell mass towards the endometrium. There are mechanisms that ensure this is correct, as seen on the image, but we don’t need to know this
which part of the female genital tract does apposition occur in?
uterine tubues / fallopian tubes
vagina
uterine cavity
cervix
endometrium
which part of the female genital tract does apposition occur in?
uterine tubues / fallopian tubes
vagina
uterine cavity
cervix
endometrium
explain stage of adhesion of implantation of embryo
The cells of the trophoblast fix to maternal tissues and to each other. This is achieved via a group of cell adhesion molecules, including laminin and fibronectin, together with cell surface receptors for these molecules.
after the blastocyst attches to the uterine wall, what does the trophectoderm differentiate into? [2]
Trophectoderm differentiates into cytotrophoblast and syncytiotrophoblast
Cytotrophoblasts: have a single nucleus and divide rapidly in vivo
Syncytiotrophoblasts are derived from fused cytotrophoblasts, are a multinucleated cell and do not divide in vivo
explain how invasion occurs in the process of implantation of embryo
(what is the overall aim?)
invasion
trophoblast, through proteolytic processes, penetrates into the maternal decidua and endometrial spinal arteries.
aim: It is looking to get closer to the maternal blood supply.
The cytotrophoblasts will break through the syncytiotrophoblasts in search for the spiral arteries, and when they reach there they will remodel the spiral arteries to make them much bigger
during placental formation and develeopment of the chorionic vill:
what do trophoblasts turn into? [1]
what do cytotrophoblasts do? [1]
what happens when trophoblasts reach the maternal spiral arteries? [1]
what do trophoblasts turn into: villous structures
what do cytotrophoblasts do: break through trophoblasts shell, invade the decidual tissue
what happens when trophoblasts reach the maternal spiral arteries? [1]
spiral arteries are converted from narrow to wide vessels (greater flow of maternal blood around villi)
which cellular layer froms the barrier betwen maternal and fetal circulation? [1]
villous trophoblast
during chorionic villus formation what is the blood supply like to the embryo?
At this stage there is very little maternal blood supply to embryo. The embryo exists in a relatively hypoxic environment
- An oxygen tension gradient is present
- O2 tension increases towards the maternal side
- Invasion is partly regulated by this gradient
which cell types causes the increase in size of spiral arteries during placental development? [1]
explain how this occurs [2]
cytotrophoblasts (after invading through syncytiotrophoblasts)
replaces the endothelium and smooth muscle of the arteries with themselves (i.e. trophoblasts).
as soon as implantation has occured, WHICH cells secreted WHICH hormone? [2]
Syncytiotrophoblasts secrete hCG as soon as implantation has occurred
the molecules that are thought are important to be a success in successful implantation are:
what are their roles?
Cyclooxygenase-2 (COX-2) -
Heparin-binding epidermal growth factor (HB-EGF) -
Vascular endothelial growth factor (VEGF) -
Human leukocyte antigen-G (HLA-G)
Indoleamine 2,3-dioxygenase (IDO) -
Transforming growth factor β (TGFβ)
Cyclooxygenase-2 (COX-2) - converts AA to PGE2 promotes invasion and decidualisation
Heparin-binding epidermal growth factor (HB-EGF) - involved in attachment and invasion
Vascular endothelial growth factor (VEGF) - involved in angiogenesis
Human leukocyte antigen-G (HLA-G) - inhibits antigen-specific lymphocyte response & decreases NK cell function
Indoleamine 2,3-dioxygenase (IDO) - regulated by IFNs to promote anti-proliferative effects
Transforming growth factor β (TGFβ) - regulates invasion and proliferation
as soon as implantation has occured, WHICH cells secreted WHICH hormone? [2]
Syncytiotrophoblasts secrete hCG as soon as implantation has occurred
If fertilisation and implantation occurs:
- what happens to the corpus luteum (due to which hormone) [2]
- ## what happens to progestorone levels (and why) [2]
If fertilisation and implantation occurs:
- what happens to the corpus luteum (due to which hormone) [2]
- *corpus luteum does not degenerate; due to hCG**
- what happens to progestorone levels (and why) [2]
- *maintained bc of maintence of corpus luteum -> turns into deicuda**
label A-C
A: oestrogen
B: progesterone
C: hCG
describe the levels of hCH during pregnancy [1]
what is the luteal:placental shift? [1] what does it signify? [1]
describe the levels of hCH during pregnancy [1]
peaks at 8 weeks then drops
what is the luteal:placental shift? [1] what does it signify? [1]
when hCG levels drop and cross over with progesterone - hCG is replaced by progestorone
what is an Ectopic pregnancy?
Ectopic pregnancy:
when the implantation of the fertilised oocyte goes wrong. It can be in the oviduct usually, and it will eventually rupture the tube which is extremely painful. However, this Is not the only place implantation can occur. The egg can even embedded outside the uterus (despite being rare)
which area does ectopic pregnancy usually occur?
cervix
uterus
oviduct
fallopian tube
infudibulum
which area does ectopic pregnancy usually occur?
cervix
uterus
oviduct
fallopian tube
infudibulum
