Lecture 8: Implantation and Germ Layer Formation Flashcards
Describe the relationship of the corona radiata and the zona pellucida to embryo transport
The zona pellucida surrounds the embryo until it reaches the uterus the corona radiata is underneath the zona pellucida and provides vital proteins to the cell
What are the stages in implantation?
- attachment of the expanded blastocyst
- penetration of the uterine epithelium
- invasion into the tissues underlying the epithelium
- erosion of the maternal vascular supply
Describe how the expanded blastocyst attaches to the endometrial epithelium
via the pole of the blastocyst
integrins help with adhesion of molecules that is facilitated by the trophoblast
Describe the penetration of the uterine epithelium and the invasion into the underlying epithelium
- trophoblast separates into the cytotrophoblast and multinucleate syncytiotrophoblast
- syncytiotrophoblast projections penetrate the basal lamina and invade the endometrial stroma
- trophoblastic lacunae appear
- eroded endometrial blood vessels fill these lacunae with blood
- trophoblast is less invasive at this point
Define deceidual reaction
response of the endometrial storm cells to the invading blastocyst; keeps the trophoblast from eroding all the way through the endometrial wall
cells completely surrounds the embryo and fills the endometrium and secrete Interleukin 2 which prevents the mothers immune system from attaching the baby from the mothers body rejecting
Where do the majority of ectopic pregnancies occur?
Ampullary
What are the two cell layers that are derived from the inner cell mass?
- epiblast
2. hypoblast
When does gastrulation begin in human development?
second week of gestation
What is the role of nanog and Gata 6 in the establishment of the epiblast and the hypoblast?
nanog cells are ones that are destined to become epiblast cells
Gata 6 are destined to become hypoblast cells; these can be induced by FGF-4
