Module 3: Embryogenesis Flashcards
Coexistence of male and female pronuclei
fertilization
Fusion of male and female pronuclei
Syngamy
Mitotic divisions (cleavage) –> _______________________
formation of morula and blastocyst
How does a morula transition into a blastocyst?
- Tight junctions form between the outer cells of the morula
- Gap junctions form between the inner cells
- Sodium is pumped into the space between cells
- Fluid accumulates between the spaces
- This creates a separate regions of cells called the inner cell mass (ICM) and the trophoblast
- The trophoblast becomes the embryo proper and the trophoblast contributes to the fetal membranes
Germ Cell Layers
The inner cell mass develops into three separate regions:
Endoderm
Ectoderm
Mesoderm
Region that gives rise to digestive system, lungs, liver and kidney?
Endoderm
Region that gives rise to skin and central nervous system?
Ectoderm
Region that gives rise to Heart, muscle and bone?
Mesoderm
- Formation of the inner cell mass and the trophoblast
- Development of ectoderm, mesoderm and endoderm
- Development of the yolk sac
- This will regress in most mammals - Formation of the components of the fetal membranes
* Allantois
* Chorion
* Amnion and amniotic cavity
Early Embrogenesis
Function of the extraembryonic membranes in mammals:
Yolk Sac _____________
regresses
Collects embryonic waste
Allantois
outer aspect of fetal membranes that will interface with endometrium
Chorion
fluid surrounding conceptus - shock absorber
Amnion/Amniotic cavity
What eventually fuse into one structure?
Chorion and the allantois
Ultimately what does the embryo need to do to survive?
- Form extraembryonic membranes
- Attached to the endometrium
- Form placenta
- Create an appropriate surface area for exchange
