Fish Flashcards
Where on the egg does fertilization occur?
Animal pole, through the micropyle
What type of yolk distribution do fish eggs have?
Telolecithal
What type of cleavage do fish eggs have?
Meroblastic, discoidal
What are the 3 cell types formed after the mid-blastula transition?
- Yolk syncytial layer
- Enveloping layer
- Deep cells
Which two cell types form the blastoderm?
Enveloping layer and deep cells
What event triggers the start of gastrulation?
50% epiboly
What events lead up to 50% epiboly?
The yolk cells push up into the deep cells, and the displaced cells start to move over the yolk
How are the hypoblast and epiblast cells formed?
While the epiboly is occurring, the cells at the vegetal-most deep cells involute into the blastoderm and separates the deep cells into epiblast on top and hypoblast on the bottom
What happens to the dorsal end of the embryo during gastrulation?
The blastoderm gets thicker and forms the embryonic shield. The epiblast undergoes convergence, extends, then involutes to form hypoblast. The hypoblast then intercalates and extends the embryonic shield down towards the vegetal pole over the yolk cell and forms the chordamesoderm
What is the organizer in zebrafish?
The embryonic shield
Which layer of cells is undergoing convergence and extension to lengthen the embryonic shield?
Epiblast
Why does the dorsal side of the embryo thicken during gastrulation?
Convergence of hypoblast and epiblast cells
When is gastrulation complete?
Ectoderm surrounds entire yolk cell, the animal and vegetal poles start to thicken to form head and tail
What does the Nieuwkoop centre do?
Specifies the organizer and organizes dorsal and ventral tissue formation
What happens to an embryo if a second embryonic shield is transplanted on?
Forms second body axis for gastrulation
Are the embryonic shield and dorsal blastopore lip homologous or analogous?
Homologous, common evolutionary origin
Which genes induce neural tube formation? How do they do this?
Chordino, noggin, follistatin. Inhibit BMP
Which gene in frogs is the equivalent of fish chordino?
Chordin
Where is the Nieuwkoop centre in fish?
Dorsal side of the yolk cell
What turns on the neural inducer genes in the dorsal side of the embryo?
Beta-catenin in the dorsal yolk nuclei
What does Nodal do?
Signal that is important for placing the organizer in frogs and fish
Which fish gene is the equivalent of Nodal in frogs?
Squint
Which fish gene is the equivalent of Siamois in frogs?
Bozozok
