Cleavage Stages and Placental Development Flashcards
Where does fertilization usually occur?
Ampulla
Events of fertilization
- Corona radiata
- Zona pellucida
- Zona reaction
Corona radiata
layer of cuboidal cells surrounding the egg; sperm enter by secreting proteolytic enzymes
Zona pellucida and cortical reaction
- layer of glycoproteins; acrosome reaction happens where acrosome (cap) over the head of the sperm ruptures and releases digestive enzymes that degrade the glycoproteins
- When the first sperm penetrates, cortical granules lining the ovum membrane rupture, releasing enzymes like peroxidases (cortical reaction)
Zona reaction
release of enzymes in cortical reaction inactivate receptors for spermatozoa binding on the outside of the zone, preventing further sperm from penetrating
Sperm nucleus enters egg cytoplasm and becomes…
male pronucleus
Once male pronucleus forms, the egg is now ________ and is called a _______.
fertilized; zygote
Once female pronucleus develops, pronuclei drawn together during….via….and then they….
first mitotic division via mitotic spindle; membranes break down and intermix
Cells of early embryo…
Blastomeres
After 3rd cleavage, 8 cell embryo is called…
Morula
Compaction
Separation of inner (fetus) and outer (chorion and placenta) cells
After organization of ICM, trophoblast, and blastocoel, embryo known as…
Blastocyst
ICM produces…
Fetus, yolk sac, and extraembyonic mesoderm
Outer mass fate…
trophoblast
Trophoblast produces….
extraembyonic layers (cytotrophoblast, synctiotrophoblast)