Fertilization, Implantation and Gastrulation Weeks 1-3 Flashcards
The zona contains sperm receptors that recognize what?
integral proteins of sperm plasmalemma
What is the function of the Zona (Cortical) Reaction?
prevention of polyspermy
3 phases of fertilization are_____
1 penetration of corona radiata
Sperm binding (SED1 Protein) and penetration of zona
Acrosome reaction - lysis by enzymes
What happens in the fast component of the cortical reaction?
change in the resting potential of oocyte plasma membrane prevents further sperm binding
What happens in the slow component of the cortical reaction?
cortical granules are released that destroy sperm receptors (ZP3)
What does Izumo do?
it is required for the fusion of sperm to egg
What is mosaicism?
Cells within one individual have a different genetic make up. Some cells have a normal number of chromosomes others do not.
Somatic mosaicism
mitotic non-dysjunction eary in cellular division
Examples of gonadal or tissue mosaicism
Mosaic Down syndrome
Segmental neurofibromatosis (NF1)
McCune-Albright Syndrome: GNAS1 mutations
Difference between Mosaicism and Chimerism
Mosaic= genetically different cells, same zygote.
Chimera - genetically different cells, different zygotes. (Like Fraternal twins becoming one individual).
Blaschko’s lines are evidence of
genetic mosaicism
Barr bodies are formed through what process
Lyonization
What is lyonization?
When one X chromosome is functionally inactivated
About how long does nuclear fusion take?
12 hours
The fusion of pronuclei begins what process?
embryogenesis
Cleavage is
a series of mitotic divisions
What is the name of the embryo after it has divided several times, but is still enclosed within the zona pellucida?
Morula
What is a defining characteristic of a Blastocyst?
a blastocoele
What happens to the Zona Pellucida after the blastocyst forms?
It begins to dissipate, and the blastocyst hatches out of it
What are the cells called that form the outer cell mass?
Trophoblast
What does the embryoblast become?
the embryo
What does the trophoblast help form?
the placenta
Define Totipotent
can grow into an entire organism, and even produce extra embryonic tissues
Define pluripotent
stem cells that cannot grow into a whole organism, but can differentiate into cells derived from any of the three germ layers
