Implantation Flashcards
What is the bilaminar embryonic disc composed of?
An epiblast layer and a hypoblast layer
What is the epiblast?
A layer of the bilaminar embryonic disc which forms the amniotic cavity and amnioblast
What is the amniotic cavity formed from?
The epiblast cells of the bilaminar embryonic disc. Amnioblast cells secrete amniotic fluid (these are also derived from epiblast cells)
What is the primitive yolk sac formed from?
Hypoblast cells of the bilaminar embryonic disc
What lines the primitive yolk sac and what are these cells derived from?
The exocoelemic membrane, derived from the hypoblast
What is the exocoelemic membrane?
A membrane derived from hypoblast cells of the bilaminar embryonic disc which surrounds the primitive yolk sac
Where does the embryo derive its nutrition during implantation
From the yolk sac which is derived from the hypoblast cells of the bilaminar embryonic disc
What is the extra-coelemic membrane?
An area between the cytotrophoblast and the embryo which completely surrounds the embryonic tissue by day 12
What attaches the embryo to the cytotrophoblast by day 3?
An extra-embryonic stalk of mesoderm which will later become the umbilical cord.
When does the syncytiotrophoblast start to secrete BHCG?
By the end of second week
When is BHCG present in the urine?
By the end of the second week
What does the epiblast transform into by the third week?
The ectoderm
What does the hypoblast transform into by the third week?
The endoderm
What is the ectoderm derived from?
The epiblast
What is the endoderm derived from?
The hypoblast
