Embryology Flashcards
2 divisions of trophoblast, at implantation
Synciotrophoblast: makes connection with epithelia
Cytotrophoblast: surrounds the blastocyst
What happens when the capillaries are eroded by the synciotrophoblast?
The uroplacental circulation is established.
What is the zygote called after the 8 cell stage when it starts moving towards the uterus?
Morula (morula stage)
Bilaminar disk contents
Hypoblast (primary endoderm)
Epiblast (primary ectoderm)
Amniotic cavity forms from _____
The epiblast
The exocoelomic membrane forms from ____
The hypoblast
What is the primary umbilical vesicle?
Hypoblast + Exocoelomic membrane.
= Yolk sac
What is the extraembryonic mesoderm?
It is the layer that forms between the exocoelomic membrane and the trophoblast; its job is to detach the blastocyst from the trophoblast except at the connecting stalk.
What is the extraembryonic coelum and what are its two divisions?
2 on the picture.
It is composed of:
- Extraembryonic splanchnic mesoderm (on the yolk sac)
- Extraembryonic somatic mesoderm (in contact with trophoblast)
When does the primary umbilical cavity become the secondary umbilical cavity?
The the extraembryonic mesoderm forms and there is extraembryonic cavity
The embryoblat is suspended to the chorion by the ________ into the extraceolomic cavity.
Connecting stalk.
When is the fetomaternal circulation established?
When the primary chorionic villi are formed.
From which embryoblastic layer does the endoderm originate?
EPIBLAST (migrating epiblastic cells replace hypoblastic cells, even though hypoblast is the primary endoderm). Epiblastic cells form all of the layers
Name the 2 zones where ectoderm & endoderm remain fused during grastrulation
Cloacal membrane: urogenital tract
Prechordal plate: oropharyngeal membrane
The prechordal plate induces ….
The notochord. Prechordal plate is a signalling center.
Which structure’s failure to close leads to a sacrococcygeal teratoma?
Primitive streak
Notochord main roles
Induced by prechordal plate:
Chord (solid structure), growing central to the trilaminar disk. Will:
- Induce neural plate (leading to neurulation, for CNS creation)
- Signal for axial MSK system (para-axial mesoderm)
- Define primordial longitudinal axis of the embryo
Where does the cardiogenic area form?
On top of the prechordal plate
What does the embryonic ectoderm give rise to?
CNS and PNS, inner ears, eyes, neural crest and many CT of the head.
What does the intraembryonic mesoderm give rise to?
Pluripotent cells.
Skeletal muscles and CT, blood cells, lining of blood vessels, viscera’s smooth muscles
What does the embryonic endoderm give rise to?
Epithelial linings of respiratory and digestive tracts, including associated glands
What does the paraxial mesoderm give rise to?
Somites: 31 segments, from which axial skeleton and muscles arise
What does the intermediate mesoderm give rise to?
Urogenital system
What does the lateral mesoderm give rise to?
Lateral mesoderm + ectoderm = intraembryonic somatic mesoderm (anterior body wall)
Lateral mesoderm + endoderm = intraembryonic splanchnic mesoderm (digestive tube wall)
