Axis Specification in Other Vertebrates Flashcards
Blastodisc
The cell on the top at the very beginning of cleavage. Above the Yolk cell
How many nuclei exist in the yolk cell
multinucleate yolk cell
What is the name of the single cell layer on the surface of the zebrafish?
The EVL enveloping layer
Mid layer of cells in zebrafish
Yolk syncytial layer
What does the YSL contain?
multi nuclei with mRNA and proteins important for axial patterning. It also helps pull the enveloping layer down toward the vegetal pole.
Difference between hypoblast and epiblast
The hypoblast forms a floor for the embryo connecting the cellular portion to the yolk. Epiblast is surface layer that will eventually involute.
What is the equivalent of the Organizer in zebrafish, and where does it form?
The shield forms on the dorsal midline.
What other factors are similar to frogs in zebrafish?
B catenin, Bozozok transcription factor similar to Nieuwkoop Center, Nodal,
What evidence is there the the shield is like the Organizer?
The shield inhibits ventral signaling, example being loss of Smad5 dorsalizes an embryo
Morphogenic Movements: Enveloping Layer and deep cells of epiblast
Deep cells undergo radial intercalation to thin the epiblast and extend like epiboly
What happens when the E Cadherin half-baked is removed?
Radial intercalation is no longer possible. Leads to incomplete gastrulation.
How is it postulated that the hypoblast forms?
Delamination
Epiblast cells involute, but ___ cells don’t
forerunner cells
Morphogenic Movements: Axial mesoderm
convergent extension
Why is PCP important?
It allows cells to extend filopodia in the proper direction to crawl along fibronectin.
List some transcription factors from anterior to posterior
Otx2 - transcription factor expressed in anterior for future brain.
RA - anterior and posterior, but not mid
FGF/Wnt - posterior
What are the three layers in the chick beginning cellular thing?
Area pellucida on the inside, marginal zone between pellucida and area opaca.
The posterior forms ___ to the long axis of the eggshell
orthogonal
The hypoblast forms from two sources:
The epiblast cells engressing, and others migrating forward from the posterior marginal zone.
What is the equivalent of the Nieuwkoop in chick cells?
Koller’s sickle.
Where does the embryonic endoderm form from?
Mesoderm ingresses through primitive streak.
What is the equivalent of the blastopore in the chick?
the primitive streak
What is the equivalent of the blastopore lip in the chick?
Henson’s node
In the chick embryo, where does definitive endoderm come from?
The epiblast
In the chick embryo, where does the notochord tissue come from?
From notochord mesoderm that moves anteriorly after entering Henson’s node.
What formation leads to the formation of Henson’s node?
Koller’s Sickle
How does Henson’s Node create the rest of the notochord?
It regresses and leaves a notochord in it’s wake.
What evidence is there that Henson’s Node acts like the Organizer?
Transplantation of Henson’s Node to another embryo induces a second axis and neural tube.
What two molecule presences or absences indicate that Henson’s Node is like Organizer?
Henson’s node produces Chordin, and where Henson’s node does not exist, there is BMP.
