Implantation Process Flashcards
When does the differentiation of embryoblasts and trophoblasts occur?
In week 2
What do embryoblasts differentiate into? What do they go onto form?
Hypoblasts and Epiblasts - go on to form embryo proper
What do trophoblasts differentiate into? What is their purpose?
Cytotrophoblasts and Syncytiotrophoblasts - allows us to get nutrients
What happens as cytotrophoblasts get further away?
They differentiate into syncytiotrophoblasts, form support layer around embryo blast cells
How do syncytiotrophoblasts assist in implantation?
They burrow into uterine lining and start to break it down via enzymes - implant via finger-like projections
Why doesn’t the mother’s immune system attack the blastocyst?
Syncytiotrophoblasts hide blastocysts from immune system
- Secrete factors that hide it from white blood cells
- Are multinucleated due to breakdown of cell membrane
How does being multinucleated help the syncytiotrophoblasts protect blastocyst against white blood cells?
Even if white blood cells do reach the blastocyst, they cannot fit between syncytiotrophoblasts to get to embryo as the gaps are too small
What makes up the bilaminar disc?
Formed by epiblasts & hypoblasts (layers of each)
What does bilaminar disc help establish? When does it occur?
Establishes the dorsal/ventral axis of the embryo. Occurs 1 week after fertilisation.
What surface do epiblasts form?
Dorsal surface of embryo
What surface do hypoblasts form?
Ventral surface of embryo
Where does the amniotic cavity form?
Forms a small fluid filled cavity between epiblast & cytotrophoblasts
What day does amniotic cavity form?
Day 8
When does full implantation occur?
Day 9
What have syncytiotrophoblasts done by full implantation?
Grow rapidly to engulf whole of embryo
