Early Development
of Vertebrates
Fish, Birds, and Mammals
Zebrafish Development
Cleavage in Zebrafish

What kind of cleavage occurs in fish?
Cleavage in Zebrafish

At the time of the mid-blastula transition
three cell populations form:
 yolk
syncytial layer (YSL)
 enveloping layer (EVL)
 deep cells

What is the importance of each?
Gatrulation in Fish

How does
gastrulation begin?
Gastrulation in Fish

What is the germ ring
in the developing
embryo?

How does hypoblast
form?
Gastrulation in Fish

What is the role of
convergence and
extension?
Axis Formation in Fish


How has it been
demonstrated that the
embryonic shield is
critical to dorsalventral axis
formation?
What structures form
from it?
Axis Formation in Fish

How does notocord induce neural structures
from overlying ectoderm?
Axis Formation in Fish

Where is the Nieuwkoop center and how does it
function?
What determines the anterior-posterior axis?
Cleavage in Birds

What kind of cleavage occurs in birds?
Cleavage in Birds

What is the area
pellucida, area opaca
and subgerminal
cavity?
Gastrulation in Birds

How is the two-layered blastoderm formed?
Gastrulation in Birds

What is the primitive streak?
Gastrulation in Birds

What is important about the primitive
groove?

the primitive knot or Henson’ node?

How does the primitive streak define the
embryonic axes?
Gastrulation in Birds

What is the fate of
cells migrating
through the primitive
streak?
Gastrulation in Birds

What happens to the
primitive streak?
Gastrulation in Birds

What is needed to complete the process of
gastrulation?
Axis Formation in Birds

How does the pH influence the formation
of the dorsal-ventral axis?

How do we know this is true?
Axis Formation in Birds

How goes gravity influence formation of anterior
–posterior axis?
Axis Formation in Birds

How does formation of Nieuwkoop center in
birds compare with amphibians?
Axis Formation in Birds

From where does the “organizer” in the chick
form?
Axis Formation in Birds

How is left-right
axis formed?

How has this
been
demonstrated
experimentally?
Early Mammalian Development

What makes
mammalian cleavage
unique?
Early Mammalian Development

What is compaction and when does it occur?
Early Mammalian Development

How is trophoblast different from inner cell
mass?

How does blastocyst form from morula?
Early Mammalian Development

What enables the blastocyst to attach to the
uterus?
Gastrulation in Mammals

Development is internal. What
modifications to the anatomy does this
involve?
Derivation of Mammalian Tissues
Gastrulation in Mammals

gastrulation begins at the posterior end of
the embryo
What appears to control cell migration and
specification?
Gastrulation in Mammals

precursors of ectoderm are anterior to
primitive streak

human hypoblast cells are replaced by
endoderm precursors
Extraembryonic Membranes
Extraembryonic Membranes

How does placenta
provide nutrients and
oxygen to fetus?
Anterior-Posterior Axis Formation

Where are the two
signaling centers
located in the
mammalian embryo?
Anterior-Posterior Axis Formation

How is mouse node and AVE similar to chick
and frog organizer tissues?
Anterior-Posterior Axis Formation

What kind of interactions occur between visceral
endoderm and epiblast in mice?
Anterior-Posterior Axis Formation

What is believed to be the role of the Hox
genes?
Anterior-Posterior Axis Formation

What kind of evidence has enabled us to
break the Hox gene code?
 knockout
experiments
 experiments with retinoic acid
 comparative anatomy studies
Anterior-Posterior Axis Formation

What was shown to
occur when the Hoxa3 gene was “knocked
out”?

the Hoxa-2 gene?
Anterior-Posterior Axis Formation

How has the
application of retinoic
acid provided us
information about hox
genes?
Anterior-Posterior Axis Formation

What is the connection between hox gene
expression and the type of vertebrae formed?
Dorsal-Ventral Axis Formation

What is the
connection between
a-v pole and d-v axis?
Left-Right Axis

What appears to be
responsible for
specifying the leftright axis?